Don't Be Surprised When Your Cheap PSU Blows Up

Sutai Double Power P4-500W

Right off the bat, the name Double Power promises more than this lightweight PSU (less than 1 kg) can deliver. Inside the 500 W PSU, there is a circuit board that takes up about 70% of the unit's base, with a generous 140 mm fan on top. The unit does not have a power switch.

The length of the cables and number of connectors is meager. Aside from the motherboard and CPU cables, there are just one SATA, three Molex, and one floppy connector. Using a graphics card with an auxiliary power connection requires a Molex adapter. The length of the heavily bent and uncovered cable is around 30 cm, or 12 inches.

Already during warm-up, the Sutai Double Power P4-500W gives away a serious design flaw: the airflow from the fan does not blow over the PSU components and PCB, but simply past the side of it. The air consequently flows (without doing much cooling) straight from the fan to the cooling vents on the back panel. Our airflow temperature test supports that impression, as the escaping air has nearly the same temperature as the air in the test lab.

Although this weakness alone concerned us, we decided to put the Sutai Double Power P4-500W through our tests anyway. The very first test, reviewing efficiency at 100% load, did not go very well. Even at just 300 W the PSU repeatedly shut itself down.

We managed to gather some maximum load values for the different voltage rails. The 3.3 V rail, for example, has a claimed maximum load of up to 32 A, but anything above 10 A causes this PSU to shut down, despite other rails hardly being used at all. We could not even begin to test the two 12 V rails. Rated at 26 and 14 A respectively, the PSU shut itself down long before we even got close to those numbers. At combined loads as low as 270 W, the voltages on the 3.3 V and 12 V rails were already falling below values required by the ATX specification.

Nevertheless, we conducted our tests at 50% of the maximum rated load (250 W), in order to generate some test scores. Efficiency was around 69% at this load level, and it decreased rapidly at higher loads. The efficiency reached its maximium value of 81% at a load of only 20% (100 W), suggesting that this is probably not a 500 W unit, but rather a relabeled 250 or 300 W unit. Ripple and noise measurements resulted in 3.3 V values that were already well out of the ATX specification at a 50% load, and most likely much worse so at higher loads. By the end of our testing, we could clearly smell the overloaded PSU components, and the unit was noticeably hot in some spots.

The Sutai Double Power P4-500W PSU does not have anything at all in common with a modern, reliable, and efficient power supply. The build quality is abysmal, the packaging questionable, and the results are, to put it gently, a good reason to stay away from this brand altogether. Let's take a look at its second unit.

  • jednx01
    Well, you get what you pay for. I may have spent over $200 on my Corsair HX1000, but this thing has been very reliable. (The first one they sent me was a dud, but they replaced it insanely quickly. My replacement one has run flawlessly for almost three years now, withstanding overclocking and pretty much anything I can throw at it. :)
  • WHComp
    This is my favorite article ever. I laughed the entire time I was reading it.
  • WHComp
    I don't need much power, I have a 520W seasonic unit that I love. Can barely hear it run.
  • rolli59
    In the conclusion, not only buying a PSU twice but other components as well.
    Great article!
  • cmcghee358
    This makes me nervous. All of my components BUT my PSU are top tier. I bought my PSU many MANY moons ago when I was alot less experienced. 1000W for $99.99 HELL YES.

    XION isn't as bad as these obviously, Ive run 4890s crossfired with a mild overclock on my 955. But the XION brand still makes me nervous.
  • fyasko
    modular is the way to go. i got the 550 watt antec modular with 2 12v rails it is amazingly stable. as someone who bought cheapo PSU's for years and blamed everything else but the PSU for problems, Invest in a great/not good PSU and your comuter will love you for years without fail. then you can spend the rest of your time flaming apple for fun...
  • iam2thecrowe
    Thank you Toms for finally doing an article like this. It should be known that most cheap PSU's are just rebranded versions of what you see in this article, so buyer beware. Surely there is some reason why these things are not taken off the market? how can they get away with selling crap like this at all? And labelled way above the actual specs. I've seen some bad PSU's in my time but this is beyond shocking.
  • JohnnyLucky
    Great article. I just posted a message and a link to the report over in the power supply section of the forum.
  • Marthian
    thank goodness I didn't cheap out when I first started building computers. Although I guess I did get a cheap power supply (according to some), it was 550W for $50, and lasted 2 years (first year went through a fan swap), and then shortly after the two year mark it started failing. at least it lasted 1 year longer than the warranty.
  • paperfox
    Hope this reinforces the fact that you should get an 80+ Certified PSU the first time or you'll have to buy 2 new computers.