Zalman 750W Heatpipe Cooled PSU - Test Setup, Methods and Testing

Article Index
Zalman 750W Heatpipe Cooled PSU
ZM750-HP Features and Specs
ZM750-HP Cables and Inside
Test Setup, Methods and Testing
550W Tests and Final Thoughts

Test Setup & Info:

In the past, we've prided ourselves on real-world testing.  For graphics cards, CPUs and memory, what matters is what takes place in real applications and games.  We also held that philosophy for PSU testing, but after a while, we realized that there is more to a PSU that being able to run a machine stable over a few weeks or months.  In reality, if there is a lot of ripple, this can damage sensitive traces on your $700 graphics card or $1300 CPU.  A multi-meter alone is not good enough to check PSU voltage stability.  It's for this reason that we've updated our PSU testbed, and will continue to improve the detail and quality of our PSU reviews.  That being said, we will still be testing the PSU in a system and will be including stress tests from real components in the real world.

We have purchased a Tektronics TDS2002 60MHz Dual Channel scope and it has become invaluable around the shop here at BCCHardware headquarters.  I've used it to troubleshoot everything from PSU's to Radars, and we are using it today to check the stability of the Zalman ZM750-HP 750W PSU.

 

Test System:

 

9W Tests: 

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 very 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.  Although some may argue that the results are moot, I find them 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.

 3.3v at 9W
3.3v at 9W
 5v at 9W
5v at 9W
-12v at 9W
-12v at 9W
     
 12v1 at 9W
12v1 at 9W
12v2 at 9W
12v2 at 9W
 12v3 at 9W
12v3 at 9W

 
12v4 at 9W
12v4 at 9W

 

To start things off, we included all the voltage rails on this PSU to show you how flat and stable the voltage lines are.  There is no ripple and very little noise on any of these lines in a no-load situation and this gives us some hope for loaded tests down the road.  The noisiest +12v rail is #4 and it is a mere 34mV.  The 3.3v and 5v lines are also very stable at 26mV and 24mV respectively.  Power Factor was measured at 0.97 and it looks to be a very efficient power supply at this point.


280W Tests:

Next we fired up the system, booted into Windows and took some reading with our Quad Core Q6600 at 3.0GHz with our 8800GTX SLI setup running idle.  Without doing any work, this system draws 280W of power with this PSU.  Below are a few of the interesting readings taken at 280W.  You can click through the gallery to see all of the images and they will all be recorded in a chart toward the end of the review.

 3.3v at 280W
3.3v at 280W
5v at 280W
5v at 280W
12v1 at 280W
12v1 at 280W
     
12v2 at 280W
12v2 at 280W
 12v3 at 280W
12v3 at 280W
 12v4 at 280W
12v4 at 280W

 

Things changed up a whole bunch once we added an average load.  When a load was applied, we saw the 3.3v jump to 60mV and the 5v line climb to 58mV.  This is outside of the standard ATX specification, but is within the relaxed limitations set by Zalman on this PSU.  If they climb anymore when a larger load is applied, they will be out of Zalman's range as well.  The 12v lines are an interesting story as well.  The +12v1 line rocketed skyward to 116mV noise and is one of the noisiest lines we've seen.  It stays under both ATX and Zalman spec though, but it is darn noisy regardless.  This 20 Amp line is the 4-pin/8-pin Motherboard connector and that is all.  It's weird that it is so noisy when it isn't being pushed to the limit.  The other 12v lines are all well within spec, and total Power Factor was 0.98.

On the last page we'll take a look at some 550W tests and see how this unit holds up when we put a couple of PCIe adapters on the Molex lines and force feed it to a couple of hungry 8800GTX graphics cards in SLI.