i'm sure quad 9800 SLI with HR 03s or S1s and an array of 100 2.5" drives would need 1kw or something. and still be quiet.

(ignore my PSU in my sig, it was on sale for super cheap black friday. and it had racing stripes. who can resist racing stripes?)

Amazing. Ok, now we need a 400W version with a fan that never ramps up...

Wow....Isn't that something...20db at 400 watt load. Maybe those crazy skull trail, quad sli, over clocker freaks might just be able to make a whisper quiet system after all. I wonder what's causing the ripple to go out of whack at the higher loads though. Maybe it has something to do with the six 12v rails?
Great review BTW

Exactly what I wanted to post.

Incredible
Kudos for Zalman. Now just start selling less Watts.


EDIT: 1000th post! Kickass

Proving that bigger is better.....at least when it comes to cooling. Put that sort of heat-sink/heat-pipe setup in many PSUs, and they all could use a slow/quiet fan. Or maybe no fan at all like my Fortrons.....

Then there's the weight problem that Zalman has apparently neglected. The article indicates as much. This PSU would bend the back panel of many cases (if it could even fit), and maybe warp the frame of the case. Zalman should at least mention this potential/real problem. It can be mostly solved with a few extra brackets or straps. But I suppose a mention of a potential weight problem might inhibit sales.....

But on the upside, most, if not all, of the target-base for this PSU already has a case that either has some sort of additional support for the PSU or has it mounted on the bottom. So, it's not really a problem for most.

good review. i especially liked the point that you stressed about that extra 100W of headroom at the lowest noise level not necessarily being useful or worth the extra cost for 99% of people.

Impressive 1KW PSU, thanks SPCR for reviewing it!
I believe there are a few typos: on page 2 "The 120mm diameter spans the entire wdith of the unit." Shouldn't it be the 140 mm fan?
And on page 4 the last column in Other Data Summary seems to have wrong data - same DC output, wrong fan voltage?

I believe the finned heatsinks placed at the exahust are suboptimal, they don't cover enough of the exhaust area, an optimal design would have covered 50% more.
This PSU could be ideal for a Quad-Crossfire setup with the upcoming 4870X2 cards, which are supposed to use little power in 2D.

What exactly makes this kind of large maximum capacity PSU not eco friendly?

Thanks for pointing out the typos.... but on the Other Data Summary, there was only one error, the output on the last column was repeated from the column before. The fan voltage stayed unchanged at 4.6V till 500W, and at the other end, it reached 12.1V at 800W and stayed there to full output.


I'm not convinced it's especially eco-unfriendly, and I said so in the article -- in terms of efficiency it's as good as any down to 40W. We didn't test down to 20W simple because it seemed absurd; no one would buy a kW PSU to run it at 20W. The main difference between this and a 400W unit of similar efficiency would be the added parts and material to make it capable of putting out and surviving 1000w output/heat. If you go by weight, it probably uses >50% more material.

The wrong voltage is (as I write this) actually in the 800W column, as 21.1 instead of 12.1, I forgot to specify this.
In the 300W column there's an odd (not necessarily wrong) figure of 9 degrees, I would have expected 12, since it's between 10 and 14.
I wonder how much heavier is this PSU compared with other high wattage PSUs. The article's 'cantilever warning' is based more on weight or size?

voltage corrected. 9°C is correct -- it's just the difference in the reading from the thermal sensor at the intake and the one at the exhaust. Sometimes, they're playing catch up with each other; perhaps in another minute or two it would have been 10°C.

The caution about cantilever effect is based on both the length and the weight. It's around 7-8 pounds. I should have measured... but it's on loan for another project. (hint: new PSU tester)

Having said that, a lot of the "gamer" cases are moving to having the PSU at the bottom. Mine does, and as the PSU rests on the bottom of the case it applies almost zero lateral force to the back of the case. The screws are simply to stop in sliding about.

Now you have got me thinking. There is plenty of space to run 2 Ultra 120 Extremes, and if you were to SLI two of the silent Asus 9600GT cards, you could have the basis of a very quiet but seriously potent system.

If memory serves, fitting an improved cooler to the 9800GX2 is near enough impossible, although I believe you can get versions with built in water blocks.

Would still be an abusively expensive system though...

Great review

Well, it looks like Zalman actually has something good going here, their heatpipe solution seems interesting and effective enough, so, perhaps all we could really wish for would be that of more sensible versions.


That Mike C, would surely be them closet overcklockers here at SPCR! this unit would be right up their alley me thinks.

great review and surprising too. I wonder if the reason the efficiency and noise profile seen in this PSU haven't made it down to lower rated models is because they command significantly lower premiums than these crazy gamer models?

I'm also perplexed by the standy noise reduction thing - if it reduces electrical noise with no detriment to anything else, why leave it off? If you never need to switch it off, why have a switch? Were the ripple measurements done with the switch on or off? Just trying to figure out the point of it

AFAIK, this PSU is based on some pre-existing Enhance ODM model. They offer a range of 800W to 1200w in the series -- hence the Zalman 850W model. The heatpipes are used in Zalman's 600W model, but that one is made by Fortron -- and FSP has always had dumb linear fan controllers, and it's not as efficient.

Your question about whether the STB switch was on is a good one. I think the answer is yes, it was on during load testing. It did not get turned off. Not sure whether it would have had any effect on ripple; I'd guess not.

The 850W Zalman in the EPCN Extreme Gamer 22DBA PC actually measured higher ripple right across the board, but there was no misbehavior of any kind with it during testing.

Turning it on increases standby power draw -- It was reported in the Other Data Summary:

Actually there are situations when a 1KW PSU isn't overkill. When talking to Tyan I was recommended to use a PSU capable of providing 1100W with their S5397. They claimed that this was the only way to guarantee that it would be stable...

1100W?

I have no idea exactly what kinds of nightmarish load out they envision for this MB.

As a sanity check the S5397, with two Xeon 5472, 2 x 2GB FB-DIMM, a single HDD, and an old GF6600, all stuffed into a Antec P190 with the funky dual PSU config, pulled 142W at the wall (230V) when idle. 142W at idle was way below what I'd expected, but I believe the load figures will prove to be rather high. I'm also going to take a look at what the system pulls under a normal workstation load, which is usually more important for a machine like this.

The real question is if the P190 PSU configuration with a 650W PSU for motherboard and graphics, and a 550W PSU for everything else will be able to keep a machine such as this happy. If not then this Zalman PSU might be the ticket to keep this machine reasonably quiet.

While the S5397 motherboard and the Xeon 5472 processors isn't what first comes to mind when talking about a silent PC there are still situations when you want to keep noise as low as possible even for a workstation or server based on components like this. In such situations a quiet 1KW PSU is indeed well worth having.

I know that if you are running a system with 2 x 9800GX2 in SLI that nVidia recommend running a 1200W PSU to guarantee everything under load.

Did the 850W Zalman have STB switch? It would seem to present pretty good value for high end gamers since it's only 10-20€ more expensive then HX620 or Modu82+ 625.

I have say it again, but I'm still amazed at Zalman for pulling this off. It's not just the fan controller, but for once they actually picked up a decent fan. I would like to see more of that with their coolers as well.

The fact that they could pull off a 400W model without a fan controller just gives me the thrills. I wouldn't mind seeing that in the near future from any manufacturer.

Put in another 14 FB-DIMMS for another 100+W DC, add 5HDDs more and you'd be closer to 400W with the same graphics card. In idle, that is.

Yes I know that adding FB-DIMMS will raise the power requirements. Add enough of them and they will keep you warm through the winter...

HDD's on the other hand is not that big an issue. Until you go 10+ you hardly have to think about them, unless you've been using a shoddy or underpowered PSU that is. I've built some 40+ disk storage servers, and usually they make do with a PSU in the 1300 - 1500W range. High quality PSU's of course, and as it's server hardware they are loud as H!

This particular machine was built to test the 5472 processors. Power requirements, cooling, and performance will be tested. It shouldn't even have the GF6600 as the S5397 has an integrated graphics controller. I had a mental meltdown while building and forgot about the integrated graphics, so whenever I get the time I'll pull the GF6600.

The P190 was just what I had available at the moment, and as a bonus it's quiet enough that you don't have to yell at each other, something appreciated by my co-workers.

If the PSU's in the P190 prove inadequate I'll certainly look at getting one of these Zalman PSU's.

Yes, it does. It looks identical to the 1000W -- even internally.

Post Summary - Longer than necessary but (1) Zalman ZM850-HP is also extremely silent and nearly perfect (4-pin 12V cable shorter than other PSU's and does not allow optimal cable management in certain circumstances) & (2) justifying PSU overkill in the name of silence

Although I rarely post, my quest for quiet PC's has been ongoing for years and I share the enthusiasm of this site. I say this b/c the satisfaction with my recent purchase (installed this week) of the Zalman ZM850-HP was going to result in a general post in the power supply forum about this PSU perhaps being the new silent king (& suggesting that SPCR review it, especially since it's inclusion in commercial PC spec'd by SPCR, the Extreme Gamer 22DBA). Well, no need to say that now given this review.

(1) While I cannot attest to the 1k version, the ZM850-HP is silent. As a frame of reference, I have what I would refer to as a silent Seasonic S12 (500w) in an HTPC. I was hoping to accomplish similar silence with a higher output PSU. The ZM850 is just as quiet as the Seasonic. In short, when you turn them on, even outside of a case, they are inaudible.

And, certainly, not all high output PSU's can say the same despite marketing representations. Having seen the Cooler Master 850w on sale for $70 AR and reading numerous reviews indicating that you could not hear it, I decided to purchase the unit. After going through 3 of them due to their noise level (quality control is poor, customer service was poor (~2 months to do 2 cross-shipped RMA's, and CSR's (or should I say CSR - they seemingly have 1) misrepresented the status of the RMA's) and the noise level on none of the units was anything near 16db as represented by Cooler Master....in fact, I could hear the fan 10-15ft away and it was the loudest part of a PC with 6 speed controlled fans and 2 x 8800GTS 512mb), it was time to end the frustration and start anew. A weekend of research led me to two units - Silverstone ST85F (completely modular) and the Zalman ZM-850-HP (partially modular....I started researching the 850 after I saw its inclusion in the 22DBA). While most reviews indicated that the ST85F was extremely quiet (& could not be heard when powered up), I was concerned by a few reviews that found it quiet but certainly audible. The few reviews of the ZM850-HP all commented on how silent it was (& a quick PM to someone who posted on this forum who purchased the zm850 also confirmed its silence). Another factor was that the fan rpm increased at an earlier load output than the Zalman and, iirc, at a much steeper incline (such that it's max rpm kicks in much sooner than Zalmans). Despite the price (ST85F was about $50-60 less AR) differential, and the steep price of the Zalman, I went for the Zalman. I couldn't be more pleased. Well, actually, 1 issue - the 4-pin ATX 12V cable is not long enough to permit optimal cable management in instances where the PSU is at the bottom of the case and the 12V MB header is at the top of the MB. With the prior PSU's (an ultra V-500 & the Cooler Master), I could snake this cable behind the motherboard plate and over the top to the input....the cable on the 850 is not long enough so for now it spans over the video card, cpu hs/fan, etc. although I've ordered an extension cable to resolve this.


(2) When deciding to replace the Cooler Master 850, I considered purchasing a PSU with lesser output in order to increase the likeliness that I would once again find a PSU that provided blissful silence & it would save me some $. After all, SPCR's top-rated silent PSU's were 650 or less. And, I know my setup does not require an 850w PSU (Athlon x2 89w version at 2.6ghz, 4gb DDR2, 2 x 8800GTS 512mb, 1 7200RPM HD (the 2 platter WD640), 2 optical drives, 6 fans & a flash card reader). In fact, a power calculator indicated as moderately reliable by others seems to suggest the draw would be ~400w. Alas, I felt it proper to consider the rpm of the fan of a psu that was drawing 400w +/- 100w (ie. I'm not sure how accurate the power calculator was & didn't want to break out the math so I used that as a margin of error) and not the rpm at idle or less. As indicated by SPCR, most of the top-rated PSU's are far from silent when drawing a significant load in the 400-500w range and none of them were at 500w or above (see http://www.silentpcreview.com/article834-page5.html ). After such consideration, I felt that it was only with a 750 or higher PSU that I could "safely" (ie., increased probability that I would not pay 15% restocking fee to return my "silent" PSU b/cit's loud when playing games) have a silent PSU. In short, I wanted a PSU that could put out the wattage drawn by my setup without needing to increase its fan speed (I also took into consideration that the maximum efficiency of many PSU's that I researched were at the 35-60% load range so you get that as an added benefit - however negligible). That being said, I did come across others who share this theory although I'm not sure it's been widely adopted b/c of the simple fact that before the Zalman line, most high output PSU's just weren't quiet enough for such a consideration. I think the Zalman ZM850 & 1k certainly make such consideration appropriate.

QFT

Enermax, Seasonic you out there? Want to be the #1 undisputed KING on SPCR? Talk to this OEM manufacturer, and make a 400w psu that can maintain a 20dba noise signiture for its entire power range, and peak out around 90% effeciency on 240v, and you'll likely never get bumped from the top spot ever.

The only reason your higher rated power PSU's tend to be on top, is because we have to overcompensate for the fact that you never make PSU's who's fan speeds stay low for the entire power range. So to get a 300w psu that is quiet, we have to buy a 600w psu. Which to me, is really assinine.

Is it possible that the quality of the parts necessary to withstand the power output/heat in a PSU putting out 400w with so little airflow from a 20dba fan are such that it is uneconomical to do so b/c the cost is essentially the same as that to manufacture an 850w psu that is 20dba at 400w (like the zalman 850 or 1k) (ie. those high quality parts can be spec'd to support a 400w 20da or for an 850w psu & thus are sold at the same price no matter their use....thus, the cost to build the 400w 20dba is the same as the 850w that is 20dba at 400w). As such, there isn't going to be a market for a $200 400w 20dba PSU b/c people would simply opt for the 850w psu that is 20dba at 400w (& comes with free headroom), and there isn't going to be a $99 400w PSU that does this b/c the cost of production given the components makes it uneconomical (or certainly not profit maximizing since for the same cost of inputs, you could rate it for 850w & sell it for $200....or $150....or etc.) Pure speculation....

You have a reasonable speculation. For similar reasons, silencers use the same huge heatsinks that OCers do: They use the cooling headroom to run their fans slower and quieter. Only a PSU maker could commit fully on the validity of your parts speculation, however.

As test shows it ,on 600w ,the two best psu are equal ,so Z managed to master the noise until there ,that is the plus for silencers;) And yes it has a price ,call it novelties ?The fact is ,it 's dangerous to mod a psu ,some OCers do adding giant rads,you at spcr replace fans,so I'm shifting from you to OCer's site. PS :I dont like xtreme cooling ,but that Z is Silent Air Cooling It is an element of a spc!Question! Is it the best cooling or better to come?[/i]