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 Post subject: A relatively silent dual CPU quadruple GPU PC - possible?
PostPosted: Fri Dec 07, 2012 2:42 am 
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Thank you SPCR for testing out higher powered PSUs and measuring their dBA under rigorous conditions.

I'm building a rendering working station for my home office. I've got hold of a couple of Xeon X5650 (so 12 cores, 24 threads), 3xGTX580s and a Quadro card. I plan to overclock the Xeons to 4.0Ghz using the EVGA SR-2 motherboard, and water cool the system (the GPUs as well). Of course I realise I have partly incompatible goals, but with that in mind, under these constraints I'm trying to get the most silent PC possible. The radiator (Mo-Ra 3) and fans will be remotely installed right underneath the office in a cool basement.

I've calculated the total power need to around 1675W using the "extreme" psu calculator.

Since so much power seems to be necessary, although it should probably be taken with a grain of sale, I'm considering using two separate power supplies. The SuperFlower Golden King 1000W Platinum received rave reviews for its noise levels here on SPCR, and isn't really any more expensive than lower powered units from other suppliers. However it doesn't have a MOV, which I understand can be custom installed by the user (voided warranty).

I've also considered using two AX860i's, two Seasonic 1000, one Enermax Platimax 1500W, the EVGA 1500W, and the Lepa 1600W, although the latter was discarded early on for being too noisy.

Any suggestions for the PSU?

BTW, it would be very interesting, for my needs, to test out the really powerful PSU such as 1500W units in terms of their noise performance here on SPCR.


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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Fri Dec 07, 2012 4:49 am 
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Gadgety wrote:
I've calculated the total power need to around 1675W using the "extreme" psu calculator.

That's going to be quite an overestimate. They always do, then many end users end up putting an extra 50% on top again and you end up with twice the PSU you actually need. The actual market for PSUs of this size is very small so not something you'll find reviewed that frequently on SPCR. Although you might think a Platinum PSU as being the only option, Seasonic do have a Gold rated X-1250 which might be sufficient.

4xGTX580s is pretty much as bad as graphics card power consumption will get. The 600 series show big improvements in power efficiency. I have to ask exactly what it is that needs that much GPU power and how well parrallelised it is? SLI is inherently inefficient and I would worry whether or not you're going to have all 4 of the cards in consistent use. Given the sheer levels of power involved, unless you are going to overclock them I would undervolt them with a BIOS mod. You really could save 100W this way.

As it will be a dual processor system you will be running E-ATX form factor I guess. Some of the big Silverstones might be of interest or the Antec P193 or the Fractal Design Define XL. You might be using an external water cooling setup but there will still be a lot of heat to clear from the system, best done with a positive pressure and a number of large, slow turning fans.

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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Fri Dec 07, 2012 7:14 am 
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edh wrote:
Gadgety wrote:
I've calculated the total power need to around 1675W using the "extreme" psu calculator.

That's going to be quite an overestimate. They always do, then many end users end up putting an extra 50% on top again and you end up with twice the PSU you actually need. The actual market for PSUs of this size is very small so not something you'll find reviewed that frequently on SPCR. Although you might think a Platinum PSU as being the only option, Seasonic do have a Gold rated X-1250 which might be sufficient.

4xGTX580s is pretty much as bad as graphics card power consumption will get. The 600 series show big improvements in power efficiency. I have to ask exactly what it is that needs that much GPU power and how well parrallelised it is? SLI is inherently inefficient and I would worry whether or not you're going to have all 4 of the cards in consistent use. Given the sheer levels of power involved, unless you are going to overclock them I would undervolt them with a BIOS mod. You really could save 100W this way.

As it will be a dual processor system you will be running E-ATX form factor I guess. Some of the big Silverstones might be of interest or the Antec P193 or the Fractal Design Define XL. You might be using an external water cooling setup but there will still be a lot of heat to clear from the system, best done with a positive pressure and a number of large, slow turning fans.


Thank you. It's 3xGTX580s and a small Quadro card (according to the numbers I've seen - around 60W!) Well, I figure the number of watts/amps is overrated as you say - taken with a grain of salt. Form factor is HPTX. Case wise it's either the Lian Li PC-90 or the Xigmatek Elysium. The Lian Li has 30+6 cm (with extender) capability for possibly 2 smaller PSUs, the Elysium handles two in the chassis. I prefer the Lian Li, but if I get the 19cm long X-1250 and it turns out power is too low, it'll be hard squeeze in another PSU. Those drive bay solutions are max 450W, and I don't know how noisy they are. I'm using the GPUs for rendering.


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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Fri Dec 07, 2012 8:22 am 
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Gadgety wrote:
It's 3xGTX580s and a small Quadro card (according to the numbers I've seen - around 60W!)

Ah, OK. I'd assumed it would have been a Quadro GTX580 equivalent but at least you're keeping the power down somewhere! Is this smaller card just for driving the monitors and the big cards for the actual crunching? The latest Intel onboard graphisc will happily drive a pair of high resolution monitors and might be worth considering as an extra power reduction and a possible form factor shrink. HPTX is a non-standard motherboard size so unless you are really set on it or already have it, EATX is more widely available and gives you many more case options. Looking at those EVGA motherboards, they are going to be very power guzzley!

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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Fri Dec 07, 2012 8:41 am 
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Wouldn't it make more sense to put the PC in the basement and run cables to your desk?
That way you don't have to worry about noise and you don't have to build a watercooling loop.
If the distance between basement and desk is bigger you can run vga and usb over cat5 for at least 30m (probably more with cat6).

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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Sun Dec 30, 2012 4:56 am 
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how exactly can you run 2 power supply in 1 computer? And how can there be space? Does any1 has photo of rig that embedded 2 power supply?


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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Sun Dec 30, 2012 6:59 am 
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Happy Hopping wrote:
how exactly can you run 2 power supply in 1 computer? And how can there be space? Does any1 has photo of rig that embedded 2 power supply?

Some cases have a space for a second PSU. The Silverstone TJ07 is an example. There are also adaptors for powering up the second PSU.

Here is an exceprt from an article about dual PSUs:

Quote:
The short answer: Don't.


The vast majority of people who use two power supplies don't need to, and waste money or endanger their rigs doing so. It's only a valid approach in a very small handful of scenarios, and is otherwise either an unnecessary over-complication, or a dangerous jury rig solution.

The main thing people do wrong with dual power supplies is to think they even need it. They look at a GTX580, then look at power consumption charts and think "OMG 500W OMG OMG NEED MOAR POWER" when in fact that's the total system power consumption; the card itself only pulls ~300W. So then they decide to supplement their already more-than-sufficient 650-850W PSU with another PSU, wasting money and making life more difficult, what with having to stash another PSU somewhere inside their case and hiding a bunch more cables.

The next worse thing people do is do dual PSUs with cheap units. Most power supplies under $100, and all under $50, use a technology called "group regulation" to reduce costs. There's a bunch of technical stuff I could throw at you; but the gist of it is that the current on the +12V and +5V rails on a group regulated power supply must stay within a certain approximate ratio to one another (say 3A of +12V for every 1A of +5V, +/-20%) or else the voltage regulation will go out of whack. +12V load too low? +5V voltage drops and +12V voltage soars. +5V load too low? +5V soars and +12V drops.

The secondary PSU in a dual-PSU usually has no +5V load at all, or at most 1-2A, meaning that the +12V voltage will droop significantly; on high-end group regulated units it will fall to 11.6-11.7V, which is in-spec but poor. On low-end group regulated units +12V might drop to 11.3-11.5V, out of spec or almost. Out of spec voltage (>11.4V) can cause component malfunction; bluescreens and random shut downs, and will prevent many hard drives from functioning at all.. Very low, but in-spec voltage (11.4-11.6V) can cause poor overclocking results, occasional instability, excessive wear on component power circuitry, and can cause hard drive issues over time.



Dual PSUs should only be used when both power supplies are high quality and use independent regulation, or even better "DC-DC" regulation. It's only a useful approach when dealing with systems that pull >1000W; then two quality 650W+ indy/DC-DC regulated units may be used in place of a single 1000W+ unit. Even then you may run into issues of crosstalk leading to greater effective ripple on power regulated devices (motherboard, graphics card, RAID controllers), and units that rely on +12V v-sense may suffer poor voltage regulation if the cable with their v-sense wires is not in use.



So just don't.

http://www.overclock.net/t/1177714/faq- ... r-supplies

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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Sun Dec 30, 2012 10:47 pm 
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so in the case of giant motherboard like the Asus dual xeon setup, in which that motherboard can support 4 x PCI E x 16 video card, how would you power a motherboard like that w/ 4 video cards?

I know years ago, there is external power supply that powers just video card, but I don't think you can buy those anymore


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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Mon Dec 31, 2012 9:42 am 
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Happy Hopping wrote:
so in the case of giant motherboard like the Asus dual xeon setup, in which that motherboard can support 4 x PCI E x 16 video card, how would you power a motherboard like that w/ 4 video cards?

Quite easily off a single large PSU. PSU requirements listed by manufacturers, mainstream review sites and 'enthusiasts' are massive overestimates.

The way I would build such a system is to take an existing PSU for testing and only buy a single graphics card initially. Connect up all parts with the exception of the graphics cards. Then install the base software and do some brun in testing with Prime95 and Furmark while the system is connected to a mains power meter to measure peak power consumption of the system without graphcis cards.

Then add the single graphics card and repeat the measurements. This gives you another power measurement and the difference is the power consumption of the extra graphics card plus PSU loss.

Then you need to do some sums. How much extra power do you require to run an additional 3 cards? You can expect however that the extra 3 cards won't use the same power again as they will frequently be underutilised.

Happy Hopping wrote:
I know years ago, there is external power supply that powers just video card, but I don't think you can buy those anymore

You could buy them but with modern PSUs having such strong 12V lines there is no need. From an engineering perspective they were inherently less efficient than a single PSU. Unless you have a really bad PSU, there is no reason to do this.

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Silverstone SG03B: E8200, Asus P5E-VM HDMI, 2Gb RAM, Leadtek 9600GT+S1 rev. 2, Samsung 500Gb, Seasonic X-400, 2x Akasa 120mm, Scythe Zipang 2 fanless


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 Post subject: Re: A relatively silent dual CPU quadruple GPU PC - possible
PostPosted: Wed Jan 02, 2013 12:03 am 
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Joined: Wed Jun 08, 2005 4:38 am
Posts: 253
thanks. I just remember I saw the demo by asus of that dual xeon connected on 4 video cards in some web site. I just need to find out what kind of power supply it is. Now I just need to find a silent power supply that also has PFC.


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