It's not a good power supply , very poor.
Conclusion:
We won't spend much time on the M500-GT. When a 500W power supply can't even handle 400W properly, it's not a good product by any stretch of the imagination.
The ZM500-GS, which is the cheapest 500W power supply that we've tested, is a different story. As a true budget PSU, it's not a terrible option. It has a good ripple and is relatively quiet. It's not very efficient, however, less than 80% on average, and the voltage is too low at 500 watts. If you really want to spend as little as possible on your PSU, then the Cooler Master GX Lite 500W is a better choice.
Our advice would be to try to spend a little more than the bare minimum. If you need something cheap, instead get the XFX Pro Series 550W Core Edition that we tested in our latest large group test. It's slightly more expensive than the Zalman PSU, but it's a much better power supply in general, and chances are the much better efficiency will earn you back your money.
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