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JessicaSe

legendary

Activity: 840

Merit: 1000

Quote from: RandomQ on November 04, 2013, 01:09:45 AM

I couldn't get one 7990 to stay under 95C with no case and a 20" box fan. Good luck with 4.

1. Get the 3 slot version if you can find it
2. I don't think quad crossfire works with dual gnu cards on windows

Did you undervolt and overclock? You should be able to stay at the range of 70C....

worldinacoin

hero member

Activity: 756

Merit: 500

Quote from: hamiltino on November 04, 2013, 03:45:16 AM

Thanks for all the replies,

I have put together a rig using the Lian-li 8000D(The case is big enough for good airflow.), xeon cpu, 2 psu's, asrock 4 pcie mobo, 4 7990's

cost around 5k all up.

That is quite a good bargain!

wizby

member

Activity: 66

Merit: 10

i.ve had rig with 4 7990 in open case. running undervolted from lepa 1600w. it was pulling ~1700-1750w at a wall. sadly didn't took any pictures of that chicken roaster

windows works fine with that configuration.

hamiltino

hero member

Activity: 644

Merit: 500

P2P The Planet!

.

HellDiverUK

hero member

Activity: 1246

Merit: 501

You're NOT going to be able to run even 2 7990 in a case without them melting.

I ran a pair of 7950 in a Define XL R2, with 6 120mm fans going flat out, and the cards still got close to their maximum. The heat was ridiculous.

For 4 7990, you're going to need a decent 4-slot board, powered risers, at least two ~1000W PSU, and an open frame in your garage/shed or basement.

I do question the sanity of it, even if you get the things mining reliably, they're going to be sucking a LOT of power, and not mining very much. You'd be better off with a couple of BlueFury USB miners - about 1/10th the price and do 2.5GH each using about 5W.

cdog

hero member

Activity: 1036

Merit: 500

Have you ever tried mining before? Because asking a question about using a case (lol) makes it seem like no.

Before you drop $3k, Id try a much smaller scale system, like a 2x7950.

And yes, motherboard matters... a lot... most motherboards wont fit 4x7990 - and you wouldnt want it to.

The cards would be far too hot so close together, thats why you use PCI-E extenders and NO CASE (lol).

RChevalier

member

Activity: 94

Merit: 10

Which OS are you going to be using? Linux I hope, you will have a tough time getting Windows to recognize all 8 GPUs.

verloren

sr. member

Activity: 323

Merit: 250

Quote from: RandomQ on November 04, 2013, 01:09:45 AM

I couldn't get one 7990 to stay under 95C with no case and a 20" box fan. Good luck with 4.

1. Get the 3 slot version if you can find it
2. I don't think quad crossfire works with dual gnu cards on windows

Would it be possible to run with a KeplerDynamics SigmaCool mount + 8x Antec Kuhler 620/920s? Not 100% sure if those conversion mounts will fit the 7990 though.

RandomQ

hero member

Activity: 826

Merit: 500

I couldn't get one 7990 to stay under 95C with no case and a 20" box fan. Good luck with 4.

1. Get the 3 slot version if you can find it
2. I don't think quad crossfire works with dual gnu cards on windows

johncarpe64

sr. member

Activity: 420

Merit: 250

Quote from: hamiltino on November 03, 2013, 10:07:02 PM

Hi guys,

I need advice on what case, motherboard and anything else i need to build a pc with 4 7990's inside. However most importantly what case choices are there to fit such a rig without having a build a custom one.

Really need some advice here. Please don't tell me its not worth it or whatever, the build is not for you.

Regards.

Since you will only be using 4 PCIE slots it should be easy, any motherboard then can support quad crossfire should work.. For casing, there is none that can fit in, you will need a custom case which you can find many topic about it (google it)..

verloren

sr. member

Activity: 323

Merit: 250

You're going to need a dual PSU system. -> https://hashcat.net/forum/thread-2530.html

Cooling will be an issue inside a standard ATX case (heat venting). Maybe the reliable milk crate + box fan, or run a water cooling system.

I think a standard motherboard with 4 PCIe slots and 4 risers would work.

hamiltino

hero member

Activity: 644

Merit: 500

P2P The Planet!

. No need for any more help,

thanks.

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