Which PSU for dual gtx 580?

[tha]

I plan to buy a PSU for a dual GTX580 system. Who has or had such a system and what Wattage for a PSU would you recommend?

[fivemack]

I have such a system. I bought a 1kW power supply (Cooler Master V1000 - it was on special offer at the time) for it; it uses about 600W measured with a wattmeter at the wall, so I suspect a good-quality 750W PSU would be fine. Maybe the EVGA Supernova 750?

[TheMawn]

There are too many possibilities to list, but there's a few things you can do to whittle down the list.


First think about the power. We just heard that a system like that can chug through 600W (at the wall, mind you), so let's start there.The 80 Plus efficiency ratings are well-defined on the Wikipedia page.

Suppose your system is using the full 600W. If the efficiency of your power supply at that level is 80%, you're actually pulling 750W ( !! ) from the wall and wasting 150W. Even at $0.12 per kWh, that's about $157 worth of wasted power per year (or rather, spend on electric heating instead of whatever your better option is).

At 85% efficiency you're down to 105W wasted, saving $50 per year.

At 90% efficiency, you're down to 70W wasted, saving you an additional $30 per year.

90% is somewhere in between 80 Plus Gold and 80 Plus Platinum. 80% is 80 Plus Vanilla. 85% is somewhere between Bronze and Silver. In other words, you'll want to add $150 per year to the cost of running an 80 Plus PSU and only $70 per year to the cost of running an 80 Plus Platinum PSU.


Next consider the kind of cabling you need. Specifically, at least four 6+2 pin PCI-E connectors since you need them for the GPU's.


Consider whether you want a modular PSU or not. So far I've limited to 80 Plus Gold and Platinum (no Titaniums on Newegg apparently), and 4, 6 or 8 PCI-E 6+2 pin connectors. Most of the remaining PSU's are modular, but about half actually have the "essentials" hard wired in, although in some cases that means that there's a 4 or 8 pin CPU power cable in there that you don't need that you'll have to hide.


http://www.newegg.ca/Product/Product...82E16817151121 $150 (if it had just a bit more power it would be my 100% recommendation...)

http://www.newegg.ca/Product/Product...82E16817151111 $205

http://www.newegg.ca/Product/Product...82E16817139042 $210


http://www.newegg.ca/Product/Product...82E16817438017 $130

http://www.newegg.ca/Product/Product...82E16817139010 $150


You may want to go through my steps yourself if you're not in Canada (or if you use a different vendor) as you may get different options, but these are some of the finest choices you have.

As it happens, the EVGA 750W that was recommended earlier is (as I suspected) a very good choice. The $150 seasonic one is disappointingly underpowered because it would otherwise be an absolute steal. The $200 Platinum ones are probably not worth it unless you're going for a few years.


EDIT: The Coolermaster V1000 is also rated Gold, so it is likely that your system will pull the same power as his from the wall, so the Seasonic 660 *might* pull it off. It depends on the other hardware you're planning to run, and what fivemack was running in that system. Hard drives, USB devices, whether or not the CPU is also crunching full time (and what the CPU actually is), how many fans you have cooling this thing, etc.

[VictordeHolland]

PSUs lose efficiency and max power when used at continuous medium/high load. I would play it safe and go for a 1,000W PSU from a decent brand (Corsair, Seasonic, Cooler Master, Antec).

I had a 800W Bronze PSU fail after 1.5 year, that was powering an OC-ed 2500k and 2x GTX470. It wasn't one from an established brand. But since then I only use quality PSUs. They cost a little more but save you a lot of trouble later.
Now I use a Cooler Master Silent Pro Gold 1000W in one PC and a Cooler Master V1000 in another.

Most 1000-1250W PSUs are most efficient in the 500-700W region, right around your expected wattage.
http://nl.hardware.info/reviews/5507...s!-efficientie (site is in Dutch, but graphs tell the whole story.)

[kladner]

Originally Posted by VictordeHolland

PSUs lose efficiency and max power when used at continuous medium/high load. I would play it safe and go for a 1,000W PSU from a decent brand (Corsair, Seasonic, Cooler Master, Antec).
.......

I agree. When I first started running a 580 and 570 in an AMD fx-8350 system, it was on the same 750 W Bronze OCZ supply I am running on now (with just the 580.) The setup was not stable, long term, but ran enough for me to get Kill-a-watt readings on consumption from the line. When I switched to a 1000 W Gold OCZ (curse the day, but that's another story), the consumption went down dramatically, though I don't have numbers at my fingertips.

My point is the same as Victor's, that a PSU running near it's max is less efficient, though in my case, the KW supply was more efficient, as well. My situation also involves a 125 W CPU and a lot of hard drives and fans, which probably is what put me beyond the capacity of a 750 W supply with the GPUs.

I would add that my experience is that running with minimal power capability in dual high-end GPU setups is asking for trouble.

[Mark Rose]

I'm running dual GTX 580's and an i7-4770 with 3 cores running mprime, on an Asus Z87-Pro motherboard, 4 case fans, 1 ssd, 1 hd, with power from a 750 watt Corsair CX-750m. The system pulls about 760 watts from the wall. I would be drawing 900+ watts at the wall if the power supply were maxed out. Before the adding the GTX 580's the system drew 130 watts at the wall.

The power supply has overheated when its airflow was impeded by a partially clogged dust filter, but otherwise the setup works fine. I use the Intel video for the desktop.

A GTX 580 will draw about 40 watts when idle and about 200 watts (internal) when running mfaktc. Make sure the 12 volt rail configuration of the power supply can handle that. Some older power supplies may not. The CX-750m I'm using can deliver up to 715 watts on its single 12 volt rail if I recall correctly. My OCZ ModXStream Pro 500W 80Plus in another system can't even handle a single GTX 570/670/770 due to its dual rail configuration (the GTX 970 would work though).

[TheMawn]

I've always wondered if the power supply's capacity (for example a 750W PSU) refers to the power from the wall or the power delivered to components as this can make a difference on the upper end.

According to 80 Plus specifications, there is a minimum efficiency at 100% load but it never seems to be observed that way. Honestly, though, I would usually prefer to run well below the "maximum" spec. A PSU designed to take 1300W really should take less of a beating from 600W continuous than one designed for 650W.

Whether or not the efficiency comes into play, the overall design of the PSU certainly does. A 1300W PSU is expecting to have to dump 100W - 200W away whereas a 600W PSU probably isn't. Hotter components are less efficient and tend to wear out faster.

[kladner]

In general, if you look at the specs, PSU makers report the total available DC output, in watts. These days, 12 V is, at least, the main CPU and GPU power source, though 5 V and 3.3 V still have substantial allocations. While different rails may have certain current ratings, these may be overridden by total current limits.

EDIT: I like the new avatar.

[TheMawn]

Originally Posted by kladner

EDIT: I like the new avatar.

[tha]

Thanks for all the advice. I decided to settle on a Corsair AX860.

[TheMawn]

That is a fine power supply. Corsair makes some good stuff. Some day, I would like to build a computer using only Corsair products (EDIT: where available). Their RAM is a bit overpriced, sadly.