For the longest time I have been using a power supply tester from a company called Casebuy. The unit did the job, but in a very simple manner. It had a series of lights that would come, if the power supply was working properly. But the PS228 from Coolmax is a serious upgrade from the aforementioned unit. The PS228 has a large LCD that displays the voltages of the rails of the PSU being tested. This includes multiple 12v rails up to two.
Unlike my older PSU tester, the PS228 tests all the possible cables of a PSU including SATA plugs. What I like about the PS228 is that you can test every connector on a PSU after a modding section of sleeving. We were even able to to test six and eight pin PCIe plugs as well. And if you work in an IT or server environment, you can test eight pin CPU connectors as well.