power consumption of i7 gigabyte 4 ghz bundle?

robinlawrie · 19 Nov 2009 at 20:35

im considering building a small renderfarm using the gigabyte 4ghz i7 bundles, since their bang for the buck beats out anything else ive found.

I was initially looking at 2u rackmount servers that feature 4 dual xeon motherboards, for a total of 8 quad core nehalems with 48 gb of ram between them. This beast costs approximately £8k with the 2.8ghz xeons. (64 threads for rendering wooo!)

http://www.pixelution.co.uk/Products/computers/2U_quad_dual_cpu_rackmount_system.html

these boxes share a common beefy psu between the 4 discrete motherboards.

so i was thinking (i know its possible) to hotwire a great big psu to run 2 or even 4 of these bundles, in a big custom case. this leads to less noise, cost, a smaller box, and slightly better efficiency.

Since i dont need anything other than a basic vga card for each, i was just wondering if anyone has measured the actual max power consumption of one of these bundles going full tilt? the cpu is about 150w alone....

also any thoughts on the idea in general?

JonJ678 · 20 Nov 2009 at 00:07

It's definitely possible to run multiple systems from a single psu. I'm not sure of the details, the atx connector can be split to run two boards so the 8 pin cpu power probably can be too. Choose power supplies you trust for obvious reasons, I suspect my 860W pc p&c would run four boards with no complaints but I'd want to check with them first.

Do they need graphics cards attached after setting them up? I thought you submitted the job over ethernet, the computers process then return the result over ethernet.

When you say custom case, how much effort are you willing to put into it, and what fabrication approach do you have in mind? Is this something you'll put together in your garage, a workshop, or contract out? It's possible to fit four matx boards into a very small space if you're so inclined, they're only 9x9x3" or so after all. If you put an ek lt on each cpu with 90" barbs the tallest thing on the board is the ram, and you can just stack the things with half a dozen standoffs between each board. If taking this approach all you'd need is a radiator somewhere and some fans blowing air sideways across the boards. Keeping them so close to each other should simplify using one/two psu's to drive the system.

Before getting too sidetracked I should mention that I don't know what an i7 system without graphics card draws. I'd estimate 250W total at 4ghz. However I'd be much more willing to run the boards in pairs, probably using 600W corsairs than all off a single psu. Look into using the 12V pci-e line to drive the 12V cpu1 line, can't think of a reason why this wouldn't work.

First thoughts are that it would work, and multiple 4ghz processors make more sense than multiple 2.8ghz processors to me. I think the pricing will work out crudely the same overall for 8 processors @ 48gb ram whether you use dual socket boards @ 2.8ghz or single socket boards at 4ghz. This depends on things like what value you put on your own time and details of "custom case". If what you want is small, quiet, ludicrously powerful and are willing to spend the time to make it so then multiple 4ghz boards are the way to go. If you want it up and running with the minimum of fuss, it's going to be the 8k option you've already found.

robinlawrie · 20 Nov 2009 at 10:16

yes i was considering to run either 4 or 8 of these bundles, watercooled in the smallest box i could manage.. thinking to put one of these:

http://www.overclockers.co.uk/showproduct.php?prodid=WC-009-AQ&groupid=962&catid=1523&subcat=

on the front or back of a custom mdf or acrylic case (i have access to a very good cnc workshop with spray room) im leaning towards mdf since when i spray and finish it can look like gloss plastic, and will have very good sound insulation properties..

the 9 fans on the rad would draw air from front to back of the case, between the motherboards, cooling the ram and chipset.

since you control the nodes using remote desktop, the gpu isnt strictly necessary, but im not sure if a pc will boot without a vga plugged in.

one thought i should consider is the whole 3d rendering world is desperately trying to perfect gpu accelerated rendering at the moment, and this would mean id need to be able to add a stack of beefy graphics cards in the future. This would obvously change the power requirements and dimensions drastically.

is it possible to get right angle adapters for pcie16 slots?

JonJ678 · 20 Nov 2009 at 10:53

I don't think that radiator is particularly respected actually, though I'd have to look up benchmarks to be sure. It's definitely worth comparing its performance to 2/3 triple thermochills even if the thermochills do cost more. Otherwise that's pretty much what I had in mind.

You have a point re gpu, I'm sure it would be easy enough to implement but I'm also sure that if I try to boot without a gpu the board whines at me and refuses to start. I'll have a look through the UD5 bios for something which looks likely to solve this, though its probably worth asking Asus/evga directly.

GPU acceleration changes things completely. I think the only sensible option is to build assuming it isn't possible, and when this changes in the future put a new case together. You'll need more power supplies, a lot more space, and either accept it sounding like a hurricane or using significantly more radiators. The effort involved in producing a case that is currently suitable and can cope with the gpus is likely greater than just making two cases.

You can get right angle adapters, though they'll swiftly make it difficult to fit multiple cards on one board if you have gpu acceleration in mind. For fitting a single gpu to persuade it to boot it would be fine. I wonder if you can get dummy plugs that fit into pci-e slots to fool the board into booting.

CNC is probably excessive but would definitely work, are you putting the design together yourself?

robinlawrie · 20 Nov 2009 at 12:41

yes im sure i could do it without cnc, but since i have free access, and generally design stuff in 3d anyway, it makes a lot of sense... some super accurate 45 degree cuts with biscuit joints will look lovely

)

ill check up about that radiator, and how it compares to other options.. just a thought experiment at the moment.. id need a big animation comission to justify building the thing!

robinlawrie · 20 Nov 2009 at 12:49

one option re. the gpus would be to stagger the motherboards horizontally, so the gpu on the bottom board sits beside the motherboard above.. id then have to find a mobo with the pcie16 slots near the left edge, rather than in the middle as is normal.

obviously if i decided to go this route id probably have to forget about the multiple boards on one psu option (unless i can get a 2kw psu or something..)

and regarding the extra rads... hey i could put one of those big 9 fan rads on each side of the case, like a giant push-pull configuration with 4 pcs stuck in between...hehe