Zalman 750W Heatpipe Cooled PSU

Print

Product: Zalman 750W Heatpipe Cooled PSU
Provided By: Zalman USA
Price: ~$165.00 CAD.

 

Introduction:

We've looked at a few Zalman PSU's over the past year.  Zalman has a unique type of cooling system in their latest power supplies that uses heatpipes to provide better cooling properties and keep noise levels low.  The first of these heatpipe packing units we looked at was the 600W ZM600-HP and more recently we looked at the ZM850-HP 850W unit.  Other than 100W, there are a few things that differentiate the 750W from the 850W version.  They differ in length, surface finish and number of +12v rails.  The 850W unit has an impressive six rails that can deliver enough power to run a pair of 8800GTX graphics cards and any processor you can image.  The 750W version only has two PCIe connectors and is a bit more limited by its four +12v rails.  That being said, let's take a look at this unit and see if it is still good enough to power a gaming machine.

750W Box Front
750W Box Front

 

First Impressions:

While the 750W ZM750-HP is no huge monster, the box still feels pretty hefty.  Although size and weight really don't have a lot to do with quality, a PSU that weighs a mere pound doesn't inspire a lot of confidence.  This PSU measures about 16.5cm long where the ZM850-HP is quite a bit longer at 21cm long.  As you can see above, the top of the box looks very professional; isn't super flashy while still giving enough information to the consumer.

 

As take a look at the bottom of the box and crack it open, we are greeted by a very tidy unit that will hopefully be a bit better than the Ultra X2 Titanium we looked at recently. 

750W Box Back
750W Box Back
Open Box
Open Box

 

The PSU boasts a 3 year warranty and features 80%+ (86% Maximum) Power Efficiency rating - meaning that if you're drawing 750W from the wall, the PSU is actually only providing a little better that 600W to your system.  This is something to keep in mind if you're using a Watt Meter on the input side of things.  Coming from Zalman we already expect this unit to be quiet, and this is due to a nice quiet 12cm fan as well as some heatpipes inside the unit.

 

PSU First Look:

Measuring 16.5cm long, the Zalman ZM750-HP will fit pretty much any mid-tower, full size or even many HTPC cases that are available.  Because of the short length of this unit, I really don't foresee any clearance issues with top exhaust fans on PC cases.  If you have an especially small case, it would still be a good idea to measure before you go and purchase this PSU.

 Zalman Branded
Zalman Branded
Rear Grill
Rear Grill
 Fan Side
Fan Side

 

The ZM750-HP has a dull matte finish that hides fingerprints and dust much better than it's glossy big brother - the ZM850W-HP.  As you can see in the first picture above, this is not a completely modular unit at all.  In fact, if you've got a very basic system you won't even need to plug in any cables.  The cables that are hard-wired to the unit may be enough for some people.  If you are buying this unit though, and want to use all four 12v rails, you've probably got more gear.

The rear of the unit is well ventilated and you can see the heatpipe laden heatsinks through this wide open grill.  The entire unit is cooled by a very quiet 12cm fan that we clocked at 700-850 rpm during heavy use.  This provides adequate cooling with virtually no noise - which is what we expected from Zalman.

On the next page we'll take a look at PSU features and specifications.


Features & Specs:

Zalman is more known for its cooling products than for its Power Supplies, but with their products now reaching 1000W, they are starting to get seriously noticed by the enthusiast community.  While they don't yet have the same reputation as Antec or Enermax, they are building a reputation that should take them into the cases of many computer gamers in the near future.  Below is a list of the features of this unit according to Zalman.

Dual Heatpipes Installed for Maximum Cooling Performance and Ultra-Quiet Operation
A heatpipe with ultra-high cooling performance incorporated on the power supply’s main rectifiers enables high load operation even at low RPM for a dramatic reduction in noise levels.
 
Improved Power Factor & Reduced Harmonics through Active PFC
By implementing Active PFC (Power Factor Correction), the Power Factor(PF) is improved up to 99% while harmful harmonic frequencies are reduced to meet the Line Harmonic Distortion Requirement of IEC61000-3-2 Class D.
 
High Efficiency Design and 80 PLUS Certified
This power supply is capable of reaching a maximum of 86% efficiency (230VAC, Full & Typical Load) through its use of high switching frequency and low power-loss circuitry. This product has been certified with the 80 PLUS Power Supply Certification and guarantees a higher efficiency compared to uncertified products.
 
ATX20+4 Pin Main Connector
ATX20+4 pin main connector broadens the range of motherboard compatibility.
 
Supports ATX12V CPU 4-Pin and EPS12V CPU 8-Pin
Two ATX12V CPU 2×2(4-Pin) power cables can be combined to form an EPS12V CPU 8 Pin power cable.
 
6 Pin Power Connector for Two PCI Express Graphic Cards
Two independent 6-Pin power connectors fully support Nvidia’s SLI.
 
Module Cables
Modular cables provide organized cable management and improved air circulation inside the computer case.
 
Ultra Quiet 120mm Fan
The ultra quiet 2 ball-bearing 120mm fan maximizes the airflow and minimizes the noise level enabling a noiseless computing environment with optimized cooling.
 
Four Independent +12VDC Outputs
Four +12VDC rails supply power independently to the CPU, VGA, motherboard, and peripheral components for the highest level of stability and performance.
 
EZ Grip Connectors for ODDs & HDDs
EZ Grip Connectors for easy removal of the plugs from ODDs & HDDs.
 
Gold-Plated Terminals and 16AWG Wires
All connector terminals are gold-plated to minimize contact resistance and power lose. 16AWG (thicker than 18 AWG)wires are incorporated to minimize voltage drop during high load operation.
 
Sleeved Cables
All power cables are sleeved for easy cable management and improved air circulation inside the computer case.
 
Multiple Safety Features
Over-Voltage Protection, Over-Current Protection, Short-Circuit Protection, Under-Voltage Protection, and Over-Temperature Protection.
 
Internal Blue LED
Blue LEDs are installed inside the power supply for cool aesthetics.
 
WEEE & RoHS
Complies with WEEE & RoHS environmental directives of the European Union.

- WEEE (Waste Electrical and Electronic Equipment)
- RoHS (Restriction of Hazardous Substances)



While this PSU is not the most powerful unit on the market, it according to the label it has enough wattage for many systems running the latest games today.

 PSU Label
PSU Label

 

More detailed information in the chart below.

 

Electrical & Physical Characteristics
AC Input Range Voltage 100VAC ~ 240VAC ±10% DC Output
Frequency 47Hz~63Hz ZM750-HP
AC Input Current
(Rated)
115VAC 12A Output V. Output Load Rating Combined
Power
230VAC 5.5A Imin Imax Ipeak
PFC Type Active PFC +3.3V 0.8A 30A   160W 750W
Power Factor 99% Maximum
+5V 0.5A 30A  
Inrush Current Limit
(@ Cold start at 25°C)
115VAC 60A +12V1 0.5A 20A   720W
230VAC 100A +12V2 0.5A 20A  
Efficiency 86% Maximum @230VAC, Full & Typical load
+12V3 0.5A 20A  
DC Output
Voltage
Regulations
Output V. Regulation Range At Full
Load
+12V4 0.5A 20A  
+3.3V ±5% +3.14V~+3.47V -12V 0.0A 0.8A   22.1W
+5V ±5% +4.75V~+5.25V +5VSB 0.0A 2.5A 3.5A
+12V1 ±5% +11.4V~+12.6V Protection Features
+12V2 ±5% +11.4V~+12.6V Over Voltage Protection(OVP)
+12V3 ±5% +11.4V~+12.6V Over Current Protection(OCP)
+12V4 ±5% +11.4V~+12.6V Short Circuit Protection(SCP)
-12V ±10% -10.8V~-13.0V Over Temperature Protection(OTP)
+5VSB ±5% +4.75V~+5.25V Under Voltage Protection(UVP)
DC Output
Ripple
& Noise
Output V. Specification At Full
Load
Ambient Temperature
+3.3V 80mV Operation 0°C ~ +50°C
+5V 80mV Storage -20°C ~ +80°C
+12V1 150mV Ambient Humidity
+12V2 150mV Operation 5%RH ~ 95%RH
+12V3 150mV Storage 5%RH ~ 95%RH
+12V4 150mV Dimensions
-12V 150mV 165(L) x 150(W) x 86(H) mm
+5VSB 80mV MTBF(25°C) 100,000 hours

 

If you were paying attention to the little details, you'd notice that the actual values of the PSU indicate that it is actually capable of much more power that 750W.  We did the math on all of the rails (AMP * Volts = Watts) and came up with a total of 1231W.  Now, there is no way that this PSU can actually sustain such a load, but according to the AMP rating, the components are capable of this.  You'll also notice another interesting thing in the table above.  Zalman has relaxed their DC Output Ripple & Noise requirements of this unit.  Typical ATX specs say that 3.3v and 5v shouldn't exceed 50mV and all 12v lines shouldn't exceed 120mV.  Zalman's ZM850-HP follows these specs, but the specs for the ZM750-HP are a bit more open.  All voltage rails have been relaxed 30mV, bringing the 3.3v and 5v lines to 80mV and the 12v lines to 150mV.  If this PSU has this much ripple and noise it won't be a good thing.  Only testing will tell.

We'll take a closer look at the cables and tear into this unit on the next page.


Modular Cables:

This is one of the more unique units I've seen as it has a lot of connected non-modular cables as well as a whole bunch of modular cables to boot.  The connected cables include the 20/24 Pin Motherboard Connector, 4/8 Pin CPU Power Connector, 3 SATA Connectors and a PCIe 6 pin connector.  These are not modular - they are hardwired to the PSU.  The modular connectors include an additional PCIe 6/8 pin connectors, 9 Standard Molex connectors and 6 more SATA Connectors.  You'll notice that I never mentioned Floppy drive cables.  That's because there are none.  FDD power is provided by using an adapter cable.  There are two floppy connectors on this "Y" cable, and this can be an issue is you still use a floppy drive as well as a 5.25" fan controller that also requires an FDD connector.  They may be two far apart to reach.

 Non-Modular Cables
Non-Modular Cables
Cable Bundles
Cable Bundles

 

All of the cables are sleeved with a nice flexible material that helps maintain cable clutter while being co-operative enough to bend where you need it to go.  Below is a diagram of the cables included with the ZM750-HP.

 Cable Diagram
Cable Diagram

 

 Two Speed Fan Cable
Two Speed Fan Cable

 

Inside the PSU:

As we open this unit, please keep in mind that opening a Power Supply will completely void the warranty.  Not only that, but because of the large capacitors, you can suffer a serious electrical shock if you touch the wrong thing.  Please do not open your PSU to compare what the insides look like.  Instead, click on the images below for a closer look.

 Fan Inside
Fan Inside
 Inside PSU
Inside PSU
 PSU Inside
Cooling System

 

The heatpipes appear to cool the unit quite well as it stayed quite cool during heavy testing and prolonged use.  We managed to pull a maximum of 583W through this unit during some UT3 in SLI and it got quite warm, but remained quiet and appeared to be solid as the system didn't suffer any instability.

On the next page we'll briefly cover our PSU Test methods before we jump into full-blown PSU testing.


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.


550W Load Tests:

We've seen the Zalman PSU start off quite well with non-load and faltered a bit at the 280W load test, so it will be interesting to see how it holds up with a larger load.  Is there a reason Zalman had to relax the Output Ripple & Noise limits on this PSU?  Will it be out of spec with a larger load?  It is rated for 750W, and while we can't run this at 100% load, we can still push it with a pretty powerful system in real world tests.  We record the results with a Tektronix TDS2002 scope, and this is how it shapes up under some pretty heavy testing.  I was pleased to see Power Factor stay at 0.98 through these tests as well.

3.3v at 550W
3.3v at 550W
5v at 550W
5v at 550W

 

Once we increased the load from 280W to 550W the noise on both the 3.3v and 5v lines actually decreased and we are now within ATX spec and well within Zalman's generous limitations.  The 3.3v line measures 40mV and the 5v line measures 42mV.  These are acceptable values.

As we jump into the 12v rails, we'll cover what each rail does as we go.

 12v1 at 550W
12v1 at 550W
 12v2 at 550W
12v2 at 550W

 

The 12v1 line still remains noisy; albeit not as much.  It measures 106mV while the 12v2 line also improves and now measures 10mV lower than at 280W showing better results with more stress.

As we wrap up the 12v lines, we take a look at 12v3 and 12v4.

 12v3 at 550W
12v3 at 550W
 12v4 at 550W
12v4 at 550W

 

Both of these 12v rails stabilized as more load was drawn from the Power Supply.  The 12v3 line settled down 22mV and the 12v4 line stabilized by 6mV.  These now sit in a very respectable range and should offer great system stability when running loaded.  Although I haven't really touched on it yet, actual voltage levels in this PSU are actually a little high - even when running loaded.  At 550W load the 12v lines all report 12.4v.  The 3.3v and 5v lines are much closer to rated output, but the 12v line remains high through all of the tests.  In the non-load tests we saw the 12v lines all report in at 12.6v.  This is only 5% high and within spec, but it could be regulated a bit closer to actual required output.

 

Below are the charts that show average voltage as well as average peak-to-peak ripple and noise.

 Average Ripple

 

 Average Voltage

 

Conclusion:

The Zalman ZM750-HP PSU is a very decent mid-range PSU from Zalman.  Along with its promise of being quiet, it offers a nice powerful package of 750W with four 20 Amp 12v rails.  Zalman has oddly changed the DC Output Ripple & Noise specification for this PSU to be poorer than the ATX specification and for that we are a little disappointed.  It seems as if they don't think that this PSU will stay within the tighter spec, so they loosen it.  Even stranger is the noisy performance of the 12v1 rail - especially in medium-load situations.  It remained noisy at any load, but did manage to (barely) stay within ATX specification.  The 3.3v and 5v rails looked shaky at 280W load, but smoothed out very nicely at 550W load.  Overall, this PSU is a decent choice as it will power most systems without costing an arm and a leg.

 

Pros:

  • Very quiet PSU
  • 12cm fan & heatpipes keep things cool
  • Lots of connections for a 750W PSU
  • Stable under hefty load 

 

Cons:

  • Ripple of 12v1 line is fairly high at medium load
  • Half-modular design
  • Lack of dedicated FDD connector(s)


Because of the high ripple and noise at a 280W load, I can't award this unit a Top Pick, but it deserves to be looked at if you're building a system that requires a good PSU that is very quiet.

 

 BCCRating

 

I'd like to thank ZalmanUSA for sending over this unit for us to review.  It's been a good unit to test out some 8800GTX SLI on a large display and showcase our test rig at a gaming conference.  Please post your thoughts and comments regarding this review in our forum at the "Comments" link below.