Enermax Galaxy 1000W Question

[Xion X2]

Since I plan on purchasing at least one (and very likely two) G80's, I'm in the market for a high-end PSU, and I've been reading about the Galaxy. Has anybody read the writeup over on guru3d about it? It sounds to me like they claim it has 4 separate 12v rails that can be dedicated to nothing but graphics.

http://www.guru3d.com/article/psu/368/1/
For us Guru's most important obviously are the are five 12volts rails, I mean it's fantastic that there are two of them if you decide to do some SLI/Crossfire gaming you are good to go. There's even a dedicated 12 volts rail for your dual-core processor if you choose to do so. Anyway add up the 12 volts rails and you'll notice that you'll have 85 AMPs at your disposal.

But four 12v rails are really intended for your SLI/Crossfire compatibility, and one 12v rail for later systems with dual dual core (QUAD) CPUs.

And here they seem to verify that idea by saying the two modular connections on the back are split up to provide power to two separate 12v rails:

...The dark red connectors on your left are two additional dedicated PCI-Express modular cables, the two 12 volts rails.

From the way they make it sound, each PCI-E connector would supply an entire 17A rail to your gfx card. Just trying to get an answer on this, because I'm thinking of purchasing this PSU. Does this sound right? And do you guys think a dedicated 17A for each card would be enough (I tend to think it would)? I'm trying to get a clear idea of what I'll need, because I plan on running SLi w/ the option of going GPU-physics in the future, which would mean I'd need 4 PCI-E connectors just for the cards and one for a GPU-physics card.

Now.. anybody got a bottle of aspirin? :)

[Nanometer]

I was pretty sure that there is a whole seperate system for GPU power. There are two 12V rails dedicated to powering the GPU(s). And considering this PSU can deliver about 400watts for the 8800GTX, it will handle it like a charm.

[Helmore]

just check thier pdf file (http://www.enermax.com/english/upload/document/M20068211615350113.pdf), page 3 and 4 to be exact. So the CPU will be drawing power from rail 1 and 2, while the rest of the system will be drawing power from rail 3,4 and 5.

[jonnyGURU]

From http://www.jonnyguru.com/PSU/Galaxy1K/


12V1 and 12V2 are specifically for CPU1 and CPU2, either via the 4-pin of the 8-pin connectors. These two rails are on their own transformer capable of 34A. 12V3 provides power to the main ATX connector (20/24-pin), one of the PCI-e connectors and the fixed SATA connectors. 12V4 provides power to the other PCI-e connector and the fixed Molex connectors.

12V5 supplies 12V to all of the modular connectors. Something I had read in the past about this power supply had me thinking that the two "red" power connectors to the left of the interface panel were on a different rail than the other four. And if you take a look at the photos below, you'll see there's a "12V(A)" and "12V(B)" spot on the PCB. But there's only one 12V lead going to the modular interface PCB, so clearly anything on a modular cable is going to be on 12V5.


Discussed further:

http://www.jonnyguru.com/forums/showthread.php?t=38

[Xion X2]

just check thier pdf file (http://www.enermax.com/english/upload/document/M20068211615350113.pdf), page 3 and 4 to be exact. So the CPU will be drawing power from rail 1 and 2, while the rest of the system will be drawing power from rail 3,4 and 5.

Is there no way to use the rail 2 for graphics if you're running a single processor?

[Nanometer]

No. What would be the point anyways. The PCI-E connectors(2 of them) from the PSU are two seperate rails anyways. What more could you want. :p:

[Helmore]

Where there is a will, there is a way. So just grab your solder iron and start modding your PSU, get some cables from some electronic store and some proper connectors and of you go :p:. Or you will have to do some work on the cables, cou can see that the 12V pin #2 and #4 on the 8-pin EPS connector come from 12V rail #2, so you could also do something with that.

[jonnyGURU]

Why do you feel you have to?

I'm growing weary of this "sky is falling" attitude towards the "assumed" power consumption of the G80 cards.

The two fixed PCI-e cables alone should be enough to power a pair of G80's. If it's not... How many drives do you have!?!? If you only have as many drives as what the fixed cables can power, then you have ALL OF 12V5 AVALIBLE for PCI-e!!!

[Xion X2]

Because they're not sitting on the rail by themselves. There are other components on them. At least according to this:

12V3 provides power to the main ATX connector (20/24-pin), one of the PCI-e connectors and the fixed SATA connectors. 12V4 provides power to the other PCI-e connector and the fixed Molex connectors

http://www.jonnyguru.com/PSU/Galaxy1K/

I was just trying to figure what kind of power-draw you were looking at on those rails with other components. Trying to play it safe, in other words. The G80/R600 has been said to take up to twice as much power as current-gen cards, and current gen cards already take up to 9A (1900XT). At least that's what I've heard. If you doubled that (worst case scenario) then you would need as much as 18A to power one G80. Or you would need a dedicated rail (since the Galaxy's are 17A apiece), which those above don't appear to be. You have the motherboard cable on one and molex connectors on the other. Since 12v1 and v2 are CPU only, you'd need to run hard drives, optical drives, case fans, water pumps (in my case) and any other components off the same rail as the graphics.

I look at it like this:

12v5 for PCI-E. Fine. 9A apiece for each card (which at this point looks to be about half of what you need to power one G80/R600--possibly.) Now we need 18 more.

So let's go searching for those 18A on the other rails. Well, whoops here we have this rail pulling the motherboard and overclocked chipset on it, along with the memory, sound card, etc, so it's not going to be dedicated. I have no idea how much power all those things take, but we'll play it safe and say 9A, leaving us 9A left to power 1 of our 2 G80's with. Check.

Now let's go searching for the other 9A that we need. Well, the only rail left is powering all your hard drives, case fans, LED's, water pumps, optical drives, etc. Your average user these days has at least 3 drives.. many have four (2 combo optical, 2 HDD). A lot of users have RAID setups. From what I've heard (which may be wrong, please correct me if it is) HDD's take about 2A apiece. So, we'll play it safe again given all our possible components here and say 9A.

So we have all the power we need for our G80's, but what if we want to overclock them? And what if we want to add a third GPU for physics? Where is that going to get its power? And what headroom are we offering our G80's in the first place if in order to get them power we're maxing out the rails all the way to 18A?

Now, granted all of this is based on speculation in regards to exactly how much power G80 will consume. But from what I'm hearing, it's around 1.5-2x the power requirements of current high-end cards like the 7900GTX/1900XT, and I'll be damned if I'm going to spend 350$+ on a PSU only to have it crap out on me when trying to run two G80's and a GPU-physics card in an SLi setup. That's just too much money to waste.

Perhaps I'm being too careful, but once you've witnessed three multi-rail power supplies fail up close and personal, you start to get cautious with all of this. Especially when these PSU's are getting so expensive.

No matter, I went with the Silverstone 850ZF because it seemed like the better choice. I hope I made the right decision. I'm a tad concerned about the 12v rail dedicated to CPU2. I hope that johnnyguru is right in that you can also pull PCI-E off that rail whereas you can't on the Galaxy.

[Helmore]

Check page 12 and 13 of this manual for rail distribution. (http://www.silverstonetek.com/downloao/installation-guide/st85zfmanual.pdf) As you can see, ST85ZF's PCIe connector number 3 draws its power from rail #2 just as you'd like it.
The manual also states that:
With dual NVIDIA GeForce 7950GTX cards, please use the following combination of PCI-E connectors only:
PCI-E 1 & PCI-E 2
PCI-E 1 & PCI-E 3
PCI-E 2 & PCI-E 3
they mean 2 connectors for each card in any of these combinations, I think you will be safe if you make sure you do it this way as well.

[Xion X2]

Thanks, Helmore. That helps me breathe a tad easier.

[Helmore]

Now that I come back on it, Silverstone's list doesn't really make much sense, I mean, where is PCI-E 4? Oh well, I guess you are safest if you use PCIe 1 and 3 (that makes for rail 4 and 2 respectively) on one 8800GTX and PCIe 2 and 4 (this maks for rail 4 and 3 respectively) for the other 8800GTX and as you can see in jonny's review of this unit (http://www.jonnyguru.com/PSU/ST85ZF/), the connectors are labeled by thier respective rail.
PS. I serieusly wouldn't know what to begin without jonnyGURU's reviews and pictures, they sure help a lot on these kind of subject.

[Xion X2]

^ I think they don't list PCI-E 4 because that addresses the concern I mentioned to jonnyguru. It's the rail with all your hard-drives, water-pumps(in my case), optical disc drives, etc. I think they wanted to make sure you were pulling from the most abundant pool of power, and PCI-E 4 wouldn't be it. The other two rails are virtually free.

But since these new cards accept two PCI-E connectors, that shouldn't be an issue. You could pull from another rail in addition to the one above for more power (example- pull from 12v2 since you're not using a 2nd CPU and use rail 4 for the other card, since it's free).

And yeah, jonnyguru's reviews have helped a lot. I went searching on the web for some other PSU reviews, and none of them go as in depth as his. Basically they're along the lines of "Yeah we opened the box... PRETTY! we hooked up the connectors.. WORKS! HIGHLY RECOMMENDED!!!!!1111"

[Helmore]

Although I would like him to ad one more thing into his reviews, I would like him to add some kind of wirelength table. It's usually very hard to find any info on the length of the individual cables. I've only seen it done once and this was over at tomshardware (http://www.tomshardware.com/2005/07/11/stress_test/page23.html) and for some, the length of the cables can be a decisive factor (if you have an antec P180 or a silverstone TJ-07 for example).

[Xion X2]

^ Yeah, I agree. That would be useful. I have a SuperTower Lian Li and am keeping my fingers crossed that the ST85ZF's cables will be long enough to reach my components. Especially since I'm having to mount it on the bottom of my case because of my triple-fan rad up top.