Zalman ZM1000-HP 1000W Modular PSU - Testing the ZM1000-HP Modular PSU

Article Index
Zalman ZM1000-HP 1000W Modular PSU
Zalman ZM1000-HP Features and Specs
ZM1000-HP Cables and Inside Look
Testing the ZM1000-HP Modular PSU

Testing - 9W, 380W & 850W: 

We initially plugged the PSU into an EZ PSU Tester 3 in order to power it on for our "idle" measurements.  As noticed below, the voltage rails were fairly stable with no load, but these aren't necessarily indicative of overall load performance.  According to our Kill-a-Watt, the power draw was 9W.  We thought these results would be interesting to include and compare with other power supplies to see how they manage a non-load situation, and how much power the PSU itself will draw.  This PSU claims to have active PFC and be 0.99 efficient in this regard - our equipment showed 0.28 without a load.  With any load, the PFC measures 0.99.

 Clean 3.3v Line
Clean 3.3v Line
 Clean 5v Line
Clean 5v Line
Clean 12v Line
Clean 12v Line


No matter what type of load I put on this PSU, the voltage rails stayed clean, and had very little noise.  As you can see by clicking the images above, we captured a 16mv ripple & noise measurement on the 3.3v rail, 26mv on the 5v rail and 32mv on the 12v line.  This is nice and clean power as ATX specifications state 50mv is allowable on the 3.3v and 5.0v rails while 120mv is acceptable on the 12v rails.  Even with a heavy load the Zalman ZM1000-HP stayed well within specifications on the rails - although the 5v line strayed close to its 50mv limit there were no stability issues.


Instead of taking a ton of pictures of each voltage line under different load, we've graphed the results below.


(Click for larger chart)


(Click for larger chart) 

The voltage is very solid with the Zalman ZM1000-HP.  It starts a little above the rated value and drops only slightly on any of the lines.  The highest 12v rail (12v2) drops 0.2v and levels off at 12.2v with a heavy load.  The 5v rail stays above 5v at 5.08v - down from the non-load 5.09v.  The 3.3v line is even more solid and we didn't measure any drop in voltage when going from a non-load situation to a heavy 850W load on the entire PSU.

All of the lines are super solid and have very little ripple or noise.  All lines stay within spec, with the 5v line being the only one that wanders close to its limit when measuring noise and ripple.  In the end, it tops out at 48mv and doesn't affect stability at all.  Overall, this PSU does show a stability improvement over the smaller 850W Zalman ZM850-HP we've referred to throughout this review.

Although these two PSUs share the same chassis, cables and close specifications, the ZM1000-HP has been refined, tuned and beefed up in order to handle a greater load.


The Zalman ZM1000-HP is currently the biggest and best PSU from Zalman and it comes in at 1000W.  It pushes out a lot of watts through six +12v rails and hefty 3.3v and 5.0v lines.  While it looks almost identical to their earlier 850W ZM850-HP, the 1000W model has better voltage regulation and lower ripple and noise which in turn enables it to handle a bigger load with ease.  Using some "Y" adapters, we loaded up this PSU with three 8800GTX/Ultra cards, an overclocked Q6600 and a CoolIT Freezone Elite system.  It handled it with ease.

The only downside to this PSU is that it lacks a couple extra PCIe cables.  With six +12v rails - two of which are rated at 28A, I'd hoped for a total of six PCIe cables, but Zalman has opted to go with only four.  If you are running a Tri-SLI system, you'll have to use adapters in order to power up all of your cards.


  • Low electrical noise
  • Rated at 1000W continuous
  • Mostly modular with lots of peripheral and SATA connectors
  • Very stable with a fairly heavy load
  • 14cm and heatpipes keep it cool and quiet - inaudible over any other fan
  • Should work in all but extreme systems.


  • Only four PCIe connectors
  • No power switch


This PSU can be found for around $230 online and for a quality 1000W PSU, it's a good price.  It brings a lot of power, features and connectors to the table and leaves the noise at the door - in true Zalman CNPS style.  It is a worthy choice for a PSU even though it falls short of our Top Pick.



I'd like to thank Zalman for sending over this PSU for us to test and stick in a system for a little torture time.  If you have any questions, comments or general feedback, please post it at the "Comments" link below.  Don't forget to check out our PSU Testing methods as they will be constantly updated to show how we test PSUs.