SLRating: 8/10


Welcome to my new hobby... Attempting to blow up power supplies.

Recently, quite a few power supply companies have upped the ante with their power supply efforts.

So often, the power supply is an overlooked part of a computer.  As power supply requirements increase, so has the specifications of the power supplies on the market. The power supply companies have answered this calling with better power supply units.

This review was going to be a big power supply shootout, but I found that so many power supplies are so different in so many ways, it really wasn't fair to put them "head to head."  Is it fair to put a $200 PC Power and Cooling against a $50 Powmax?  Is it fair to put a modular Ultra X-Connect against a non-modular Thermaltake Pure Power Butterfly?  There's so many different strokes for different folks, I decided to break down the review into several smaller reviews that will be posted over the next several weeks.

So why be concerned with what a power supply can do?

The first thing I need to tell you is: Quit looking at wattage!! Wattage doesn't mean squat! All wattage is is the total capability of all of a power supply's rails. The 5V, 12V, 3.3V, -12V, -5V and 5VSB capability all added up. That total number really tells you nothing about the power supply's actual capability. And then, is that wattage continuous power or maximum peak power? There's also variables that come into play like, what was the temperature at which the testing was performed? For what period of time was the testing performed at the specified wattage? Basically, you should look at the amperage each rail is capable of and then just consider that the power supply's BEST CASE SCENARIO capability.

Now you need to figure out your computer's WORST CASE SCENARIO load. There are several calculators on-line that allow you to "add up" your computer's power. My favorite is this one. There's also a very simple one here.

Once you do this, you'll really find out how unimportant maximum wattage is, and how important the way the manufacturer distributes power across the rails is. If you have a 500W power supply with 40A available on the 5V line and you're using a Prescott with SLI video cards, you might be in trouble because the 5V line alone is using up 200W of that power supply's total power not leaving much else for other rails! Given that most power supplies give you 20 to 30A on the 3.3V (which is way high by today's standards, but even 30A on the 3.3V is only 100W) and split up about 20W for negative voltage and stand by, you're only left with 180W for the 12V rail. That's only 15A! Mind you, we're talking maximum combined peak power, but better safe than sorry, right?

If you don't have the time or resources to do this, then just do this instead: Try to figure out if your PC is going to be 5V heavy or 12V heavy, and then buy the biggest, best quality power supply you can afford with the load balanced most appropriately for your PC. For example: If you have a Pentium III or an Athlon XP board without an ATX12V connector (like Biostar Socket A motherboards never have the 2x2 connector) then something like an Antec or Raid Max with an insanely high 5V is most suitable for you. If you have a Prescott or an AMD64, consider something with a high 12V like an Ultra or an OCZ. If you have PCI Express video card or cards, consider something with a really, really high 12V rail.

All that said, fact of the matter is, if you have a power supply that has a load capability properly balance for your PC, you could actually run your machine with a quite a bit of stability with a mere 300W power supply. If you don't believe me, you might want to consider picking up a Kill A Watt. You might find that you're currently pulling about 200W from the outlet. Given that PC power supplies typically only have an efficiency of 75%, that's only 150W!! The problem here is that load balances vary greatly from PC to PC, so you might have a 500W power supply with barely enough 12V available for your CPU, drives, fans, lights and video cards because the power supply puts out most of it's power on the 5V rail!

So what will I be testing?

I will be throwing five tests at each power supply.

Test number one is the Zero Load test.  This will be performed with no load on the power supply other than the internal load the power supply provides itself to function, the load of any fans that may be installed and running in the power supply and an artificial 5V stand by load of 2A.

The data gathered on this test will be:

After this test is performed, the load tests will begin starting with a synthetic load representative of three builds

The first build is a a pretty common representation of a PC found today.  Heavier on the 12V than PC's of the past and lower on the 5V than PC's of the past.  We used a Pentium 4 3.2 Northwood, an AGP video card, 1GB of DDR RAM, two hard drives, two optical drives and three case fans. For fun, we threw four USB devices on the machines just to get the 5V load up over 30A.

This is what we came up with:

So we made our load specs for this build....

This next load test was based on an Athlon XP 3200+ on a Biostar M7NCD Ultra 400 motherboard, an AGP card, 512MB of PC2700 RAM, two hard drives, two optical drives and two case fans. 

The estimated maximum load for the build was:

To make worst case scenario even worse, we made the load specs this:

The last build is sort of gonzo.  We built a Pentium 4 3.4E Prescott with two 6800 Ultra PCI Express video cards, two hard drives, two optical drives, 1GB of RAM, three case fans and came up with:

When I replaced the Prescott with an AMD64 3400+, I had enough ceiling to run four hard drives in a RAID-5 array with room to spare.  So we decided the load test for this configuration should be:

We also took the power supply's temperature at this load.

Now, all of these builds had USB mice and keyboards as well as floppy, NIC... the standard fare.   Whether 512MB or 1GB of RAM were used, this was always done by using two sticks of RAM, which is why the voltage demand never really changed on any of the builds.  Naturally, if you had more sticks of RAM, you'd have more of a load on that rail.

This is what we're looking for with each of the above four tests:

That's right.  Same as the Zero load test! I just wanted to make sure you were paying attention. ;-)

We also took a look at the label and cranked the 12V and 5V up to maximum specs as per the PSU's label.  We then did the math: (3.3+5V Combined Maximum)-(5V * Maximum Amperage)=(3.3V Testing Amperage Setting) and set the 3.3V accordingly. 

At the point where we cranked up the 5V and 12V to label spec, we were usually already beyond the power supply's maximum wattage rating, so it wasn't unusual for a power supply's overload protection to kick in if we tried to compensate a little extra 3.3V.  This is why it ticks me off when a review site says "we ran the power supply at maximum load" but doesn't break down how the rails were loaded.  It's a given you can't load a power supply to "maximum load" if you juice up each rail, so one is left wondering where "maximum load" really is.

This also brings me to the "power supply blowing up" scenario and what it means to me and my tests.  If overload protection trips, that's good.  I actually rely on overload protection to kick in to effectively test a power supply.  If I run a power supply with a 12V load of 20A and the rail is only rated at 16A and overload protection kicks in, then no big deal.  I'm over spec.  I write down that the power supply failed the test and move on to the next test.  This is also how I do the max load test.  I set the 12V and 5V to the maximum on the label and then raise the 3.3V until overload protection kicks in.  When it kicks in, I lower the 3.3V and cycle the power on the power supply.  If the overload protection fails to function, the power supply blows up.  This does not mean that the power supply is inherently a fire hazard.  It means I received a defective unit.  Unfortunately, it also means the testing process comes to a screeching halt.

When everything is said and done, I lower the load back down to test two and wait for one minute for the power supply to cool down.  We then cut the power off and watch the Compu-Nurse.  After one minute, an idle temperature is taken.

How will the tests be performed?

I'll be honest... I don't have three builds I can switch power supplies in and out of. Quite frankly, I don't have the time to do this that way either!

For testing power supplies, I am in possession of a SunMoon SM-268, a power supply load tester, and a little Weibo PF1211, which is a mains efficiency reader similar to a Kill A Watt, but easier to read because Volts, Amps, Watts and Power Factor are all displayed on four LED's simultaneously, instead of having to click through one LCD to get all pertinent information.  Despite my wife's best attempts to convince me to set up elsewhere, the lab is in the dining room.

Everything I need is all laid out on my dining room table.  Thanks to Ultra Products for the big ol' anti-staic mat.

The SunMoon SM-268 can dynamically load a power supply at the push of a button. There's five memory settings and the ability to crank up the amperage while the power supply is already up, running and loaded. I have three memory settings set to settings that can perform the above three tests. The other two tests are set up for dual 12V rail power supplies and I'll explain those later.

In the lower left of the SM-268 is a cluster of power connectors I plug the power supply into and a toggle switch that I toggle for single 12V rail and dual 12V rail power supplies. If I'm testing a dual 12V rail power supply, I make sure I plug the 2x2 12V connector into the SM-268 because that connector gets it's power from 12V2.

Here is where I set the amp load for each rail.

With the press of a button, I can test the output voltage of each rail while it's under load.

Some math is done for me. This mode of the tester shows me how much wattage is being put out on each rail, as well as the total wattage.

The display on the SM-268 has six fields. Each one representing a loaded rail. There's a display for the 12V rail, 5V, 12V2 if I'm testing a dual rail power supply or -5 if I'm testing a single rail power supply, -12V, 3.3V and 5V stand by. With the press of a button, the displays will switch from load in amps, to voltage, to wattage. In wattage mode, I also get a display telling me the total wattage being loaded onto the power supply.

Now let's say we have a power supply plugged into the Sun Moon and it says it's pushing 300W. Now I'll take a look at the PF1211 and see how much wattage I'm getting from the mains. If it says 500W, I divide 500W by 300W and come up with 60%. This would mean the power supply is running at 60% efficiency.  The PF1211 also tells me my power factor as well.

Busting out the old school calculator and notepad for this test.

Along the bottom of the display of the SM-268 is a number of buttons.  It's quite intimidating and sometimes to accomplish something you have to push a "shift" button and another button simultaneously.  I have most of my settings pre-programmed, so all I have to do is select "memory 1," through to "memory 5."  I then have an up and down arrow for increasing and decreasing load while the tester is running.  I use these arrow buttons for bringing the juice down for my zero load test and cranking my juice up to see where the limits of a particular power supply may be.

For the record (because someone asked me this the other day,) the preset loads that I have pre-programmed into the SM-268's memory DO NOT ramp up.  The load on the PSU is immediate, so not only does the Power Good signal on the power supply have to work correctly, but the power supply also has to be able to accept a sudden, nearly crushing load, in a split second's notice.  The only tests that are "ramped" is the zero load (where I ramp down from test two) and the full load (where I ramp up from test three.)

I have a Compu-Nurse plugged in as well so I could see what operating temperatures are.  I began doing this after loading up an Antec and Enermax power supply and noticing how hot the air coming out of them were.  I also shut down an Ultra PSU abruptly after a 550W load and noticed the housing getting very hot.

What I WON'T be testing:

Along the bottom of the display of the SM-268 is a number of buttons. It's quite intimidating and sometimes to accomplish something you have to push a "shift" button and another button simultaneously. I have most of my settings pre-programmed, so all I have to do is select "memory 1," through to "memory 5." I then have an up and down arrow for increasing and decreasing load while the tester is running. I use these arrow buttons for bringing the juice down for my zero load test and cranking my juice up to see where the limits of a particular power supply may be.

For the record (because someone asked me this the other day,) the preset loads that I have pre-programmed into the SM-268's memory DO NOT ramp up. The load on the PSU is immediate, so not only does the Power Good signal on the power supply have to work correctly, but the power supply also has to be able to accept a sudden, nearly crushing load, in a split second's notice. The only tests that are "ramped" is the zero load (where I ramp down from test two) and the full load (where I ramp up from test three.)

I have a Compu-Nurse plugged in as well so I could see what operating temperatures are. I began doing this after loading up an Antec and Enermax power supply and noticing how hot the air coming out of them were. I also shut down an Ultra PSU abruptly after a 550W load and noticed the housing getting very hot.

The only thing I'm missing is a Waveform Monitor, which I think I can get off of eBay for about $100, but that's one more thing I'll need to learn how to use and right now I just want to get started with testing power supplies using the methodology I have already determined that I will use.

So without the waveform monitor, I won't be able to test the cleanliness of the rail.  This is a shame, as it's very important that a rail is not only powerful and within spec, but that it has little ripple.

There's also a few things that I KNOW I won't touch on, so let's get those out of the way so I can minimize the hate-mail now instead of down the road.....

What I'm not going to touch on

As I said, I don't have a waveform monitor so I can't test how "clean" a rail is, but it is obvious to me when a power supply's DC voltage becomes unstable because the voltage will fluctuate wildly.  Fortunately, this coincides with the voltage being out of spec (5% on the positive DC voltages and 10% on the negative DC voltages) so it's pretty easy to guesstimate the limitations of a particular power supply unit.

I'm also afraid I will not report on noise.  SilentPCReview does a GREAT job on testing power supplies for noise.  You want to check them out.  If a power supply is really quiet, I'll state it. If a power supply is really loud, I'll state that too.  But I'm not going to report noise levels in decibels, etc.  To effectively test a power supply for noise, one needs to either install the power supply into a system or have a test rig designed for the task.  One also needs to have access to an accurate sound meter.  I do not. SilentPCReview does.

I do only touch on the subject of power supply temperature.  As it is, the act of pulling out the CompuNurse was an afterthought because of observations I made regarding temperatures.  Again, this is not done to any scientific detail because I'm testing power supplies outside of a case.  A wild guess would be to say that any power supply I test will actually run hotter inside a PC than it is on my table.  This is because it's not drawing in outside air when installed into a case.  A power supply usually sucks hot ambient air in from the inside of the case because a power supply really is a part of a PC's total cooling solution.

Speaking of temperatures; I know I'm going to get some people pointing out to me that the efficiency, or even the capability of a power supply to produce it's maximum rated wattage, decreases as it's temperatures increase.  For this I will respond with... "And?"  This is an issue with most review sites that merely throw a power supply into a case and fire it up and judge it based on how well it ran in their system.  Let's say the room temperature is 25°C.  This is the same temperature that power supplies are usually tested at (there's a few exceptions.)  Let's say the ambient temperature in the case is 35°C (a little warm, but what the heck!)  Naturally, the ambient temperature of a case is going to raise the operating temperature of the power supply immediately making the power supply's "rating" inaccurate.  So when a review site tests a 500W power supply in a hot case, they may only put about a 300W load on it tops, never realizing that due to the rise in operating temperature the maximum capability of that power supply may only be 400W (using REALLY round numbers here.)  So how am I any different?  Well, I admit that I'm working in a 25°C environment outside of a case.  But as the power supply puts out higher wattage, it generates it's own heat (which of course varies from power supply to power supply) thus increasing it's operating temperature, thus decreasing it's capabilities.  Despite this, I'm still putting the same load on the power supply.  500W is 500W.  20A on the 12V rail is 20A.  One has to take in consideration that I am putting long term worst case scenario loads on the power supplies, so if it can do it's rated wattage at whatever temperature it happens to be running at for the length of time I run it at (usually an hour) then I think my point has been made.

That leads me to how OTHER SITES with load testing equipment test their power supplies.  I say:  "Label be damned!"  Fact of the matter is, the means that companies get the results they put on their labels vary wildly.  I'm not playing that game.  Typically, a review site will load up each rail based on what the label says.  The guy who showed me how to use the SunMoon did the same thing.  I immediately said, wait a minute... I buy a power supply to suit my system.  I don't build my system up to suit my power supply.  Why would I load test a power supply based on what I think it can do based on it's label?  I should load test it based on what a REAL PC would load it up at in a worst case scenario.

With my Raidmax review, you'll see that I find that the power supply, despite being "rated" at 18A on the 12V rail, ran at 20A.  I was able to obtain 20A on the 12V and 20A on the 5V and maintain stable power.  I was only able to get 469W out of the power supply without causing the overload protection to trip.  This means the power supply is NOT capable of it's label rating.  Although this is a sort of "false advertising" I'm not going to drag the power supply in the mud and state that it's crap because of it.  If I had a machine that was similar to one of my simulations that the power supply passed, I would have no reservations using said power supply.  So the Raidmax 520W is actually a 465W.  So they're trying to lie to customers by claiming it's a 520W.  That doesn't mean it's not a good 465W!  :-)


Raid Max RX-520XP

Raid Max is a company that designs and distributes cases and power supplies. Only a few years ago, Raid Max was having their power supplies built by lower end companies like Leadman. But with power supply quality becoming more and more essential to the performance and stability of a computer system, Raid Max has taken a complete 180 and now offer five seemingly better quality units, mostly built by power supply manufacturer Topower.

Their flagship power supply is the RX-520XP. A high-wattage, shiny-finish power supply that touts a lot of power and a lot of low noise features.

Here's the back of the Raid Max RX-520XP. The housing has a similar "titanium" finish as the Ultra.

Keeping things quiet and cool.

To keep things quiet, the Raid Max is built on a Topower base which features Topower's typical affair of thermostatically controlled fans mounted with rubber grommets. Then, there are four fan headers that are thermostatically controlled and run as low as 4V, so your case fans can spin slowly when your PC's ambient temperature is cool, or fast when your PC is warm.

Noise is a priority for Raid Max. That's another good reason to start with a Topower base. They mount their fans through rubber grommets.

Speaking of fans, the Raid Max also will keep your fans spinning for a full three minutes even after your PC is shut off to help cool down the computer even after it has been shut down. Something they call "ECASO" (Enhanced Cooling After System Off) You know what they say! ECASO, Su Casa!

Inside, we can see the similarities between this PSU and an OCZ, Tagan and TTGI. This is because they're all made by Topower. Note the large heat sinks.
Lots of surface area here to help dissipate heat. But there's some subtleties that set it apart from it's cousins.

Nobody likes interference!

Another attention to detail that Raid Max includes is it's close scrutiny to EMI. All of the wires are twisted to help prevent EMI. Raid Max has also added iron ferrite cores to two of the 5.25" drive power connectors, labeled VGA/HDD, as well as the AC input power cable. They have also added a few capacitors to the two VGA/HDD cables to help clean any unwanted ripple in the lines.

Good size caps, good size heat sinks, front to back air flow... This is a well built power supply.

Digging them heat sinks!

One thing I really liked about this power supply is how quiet the fans were because of how slow the fans were spinning. The main reason this worked out so well is because the heatsinks inside of the unit were absolutely huge. The sinks came up through the center of the PSU and then spread out from there essentially canopying the entire inside of the power supply with a complex network of fins. The large amount of surface area meant the sinks were able to dissipate more heat, requiring less air flow provided by the fans.

Aesthetic Overview:

I rather enjoyed the Raid Max's understated snazziness. The power supply is trick looking without looking annoying. It's the same titanium finish as the Ultra and features blue lighting (albiet blue LED's as opposed to blue UV reactive fans with UV lighting.) The Raid Max also had some nice windows on it like the Ultra, but I think the reason why I think this power supply looks a tad understated is because the fans are on the front and back of the power supply and not the back and bottom, so the lighting is not concentrated in one area.

Taking a look at the label:

RAID MAX RX-520XP +3.3V +5V +12V -12V -5V +5VSB
Max Output Current 26A 45A 18A 1A 0.8A 2.5A
Max Combined Wattage 220W 216W 12W 4W 12.5W

As you can see above, the Raid Max is very strong on the 5V rail and not so much on the 12V rail. I'm not sure why Raid Max didn't put more attention on voltage distribution. Take a look at the negative DC and 5V standby, for example. 28.5W alone is spent on those rails. Why?

What power connectors do we get?

The cables are all twisted to help reduce EMI. The two "VGA/HDD" and the ATX connectors have a shield on them.
What's funny is that if I look really close at these shields, I can see the word "Tagan" on them. Oops!

ATX connector 20+4 pin
2 x 2 12V connectors 2
2 x 3 PCIe 0
6-pin Xeon/AUX connector 0
5.25" Drive connectors 8*
3.5" Drive connectors 2
SATA Drive power connectors 2
Fan only connectors (thermostatically controlled 12V only) 4

* = 6 of the 5.25"connectors are typical where two of them have the EMI and ripple filtering on them.

Here's a close up of the VGA/HDD and the ATX connector.
The ATX connector actually has a modular design that allows it to easily become an EPS12V connector by just clipping on the extra four wires on the end (as shown.)
There's also two 2x2 12V connectors that snap together and become one 2x4 connector.

I've voided my warranty further by stripping the heat-shrink tubing off of the VGA/HDD connector to expose the iron ferrite cores and small capacitors used to clean ripple and reduce EMI.

So now it's time for some testing!

What's my opinion about what the outcome will be?

Well, looking at the label, I'll make the prediction that this power supply will pass "test one" with flying colors, since this power supply is supposedly capable of a whopping 45A on the 5V rail.  I'm not sure it will be too stable on test two because at 20A the 12V will be out of the power supply's spec for it's 18A capable 12V rail.  I'm thinking the third test will throw this power supply into a tail-spin.  In my opinion, this power supply isn't engineered for a system so top heavy on the 12V rail.

As for the temperature tests, I think this power supply will fare well.  With keeping the fans spinning three minutes after shut down, I doubt they power supply will get very hot once it's shut down.

Ok.... Enough talk!  Let's pummel the power supply!

Here are the results.  The numbers in red are numbers that are out of specification:

Raid Max RX-520XP Zero Load Test One (366W) Test Two (301W) Test Three (341W) Full Load (469W)
12V 11.48 11.76 12.34 11.33 12.44
5V 5.31 5.10 4.97 5.15 4.90
3.3V 3.38 3.26 3.26 3.24 3.24
Efficiency 45% 73% 74% 68% 73%
Power Factor .56 .73 .72 .76 .71

Temperature under load = 23.8C. Temperature after power off = 28C.

Analysis of Results:

At Zero Load, the 5V was out of spec.  Not a concern since nothing should be actually "running" at this point.  Test one was solid as I thought it would be. 

Test two was surprisingly stable.  12V went up as it naturally would with a power supply with so much 5V capability, but I thought for sure it would go above and beyond the 12.V tolerance.

Test three was still pretty damn good considering the specs of the power supply.  I thought I would see a lot more fluctuation.

The full load test proved that this is a very stable power supply.  I was disappointed that I was only pushing a total of 469W before the power supply's overload protection kicked in.  Once I lowered the 3.3V to around 3A with the 12V up at 18A and the 5V up at 45A, the power supply kept on trucking for hours on end.  Something a real PC would NEVER do to a power supply.

As I expected, the temperatures stayed low after shut down.  You just don't know how valuable this function of the power supply is until you see an ordinary power supply's temperatures sky-rocket.  Good job on including that feature guys!

In conclusion....

For features, on a scale from one to ten, I give this power supply an 8. 

For performance, I give this power supply an 8. 

It's average overall score is an 8.

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