Installation was awesome-I didn't even have to connect any of the modular cables because just enough were supplied on the device itself.
The ZM850-HP was wholly stable during the idle, load, and extended load tests. Voltages for the 3.3V rail, 5V rail, and 12V rails were 3.31V, 5.05V, 12.16V, respectively. The unit handled my Athlon X2 6000+, GeForce 8800 GTX, 8 GB of RAM, and three SATA drives without so much as a whimper. I've included the OCCT Perestroika results as proof, as well as the results of the same test on the Corsair TX750 ThinkComputers recently reviewed.
It's whisper quiet, too. The Standby Noise Filter Switch will adjust the voltage on the 5Vsb rail if it makes noise when the system is in standby. My system does not do this, so I could not see if it actually makes a difference.
I'm bugged that the unit has no actual power switch on the back. I'm one of those folks who likes to have everything connected before flipping the switch and hitting the power button. Every power supply should have a real power switch so that a user can be sure that a unit is entirely off and not using any power whatsoever. Without a power switch, a computer with the Zalman ZM850-HP always has power flowing to it. It's not only a device longevity issue, but a safety issue, as well.
I wish there was a fan monitoring connector.
The Zalman ZM850-HP is a solid unit. I'm more than pleased with its performance despite its main design flaw: lack of a power switch. The out-of-the-box connectivity is probably sufficient for most people, and there's more than enough power provided on its six 12V rails (four 18A, two 28A, for 768W max.).
The connectivity is fantastic, too. This power supply has 12 SATA connectors! That's more than any unit I've reviewed. That leads me to believe that this power supply would be perfect for a back-office server or home backup server, where there are lots of hard drives. It's also good for gaming rigs with its SLI certification.
The main points of this unit are its stability and the warranty-if ever the unit becomes unstable, Zalman will replace it, as long as it's within three years of purchase.
ThinkComputers gives the Zalman ZM850-HP 850W Modular Power Supply an 8 out of 10 score.