Quote from: Eastwind on January 05, 2014, 11:01:41 AM

Quote from: dreamzz on January 04, 2014, 09:59:42 PM

Quote from: Eastwind on January 04, 2014, 08:35:15 PM

Quote from: dreamzz on January 04, 2014, 05:53:58 AM

Quote from: Eastwind on December 15, 2013, 12:35:13 PM

I have 17X7990 in total. The core/memory voltage and frequency vary because every GPU is different. For some GPU, I can run 0.99v, with 950/1000 MHz, temperature is 70C. For others, the temperature is 85C, with 0.95V, 870/900 MHz. It depends on the position of the cards in a PC case.

I use powered PCIE risers in open case, I put extra fans to extract heat out.

The original thermal past is extremely thick. I tried to apply thin layer of thermal paste, the improvement is minimal, just 2-5 degree, as the heat sink cannot touch the GPU evenly, even after I adjusted the force with the 4 screws. That could be the reason why manufacturer apply a thick layer of thermal paste.

whats the maximum number of 7990 gpu's we can run per motherboard, can you please send me your configuration, specs of the rigs etc, I have 10x7990 cards that I am looking to put maximum per motherboard. if you can some pics would be great too. Thanks

I run 4X7990 or 2X7970+3X7990. These are all 8 GPU in total. I have not tried more than 8 GPU.
The MBs are ASUS Rampage Extreme (too powerful for mining), MSI Z77A GD55, Gigabyte GA-Z68AP-D3, ASUS P7P55D pro (LGA1156). These MB have 5 PCIE slots or more.

I use Windows 8, Catalyst 13.4 or higher as lower version does not recognise 7990. Some MB needs 13.8 or higher. I do not know why.

Hi Thanks for the reply, much appreciated. will you pass a few more information, Asus rampage(lga2011) is too expensive too

It looks like all the ones are tested are lga1155 or above. So I suppose the lga1150 will not support these many gpu's. I only have 7990 so which of the above motherboards you tested with that combination? which processor, how much ram needed, PSU requirements etc. Did you use intel processor or AMD? which one?
I dont know if this is asking too much, but it would also be great if i can get a copy of the config file.
Cheers

I would recommend Gigabyte GA-Z68AP-D3. It costs about $60. I used it to run 4X7990. The CPU is Intel Celeron G1610 (LGA1155) with 4GB memory. The memory speed does not make difference, so you can use cheap memory. The power requirement for 4X7990 is about 1680W (4X400W+80W). I use one 750W+1250W. If you undervolt and underclock, 400W is more than enough for one 7990. The setting, Core/memory = 950/1000MHz, Vcore = 0.99V. The setting varies for each card. You need Afterburner Beta to tune the 7990. Normal Afterburner does not work. The default 1.2V Vcore is too high, it needs more than 550W for each card.

The second choice is MSI Z77A GD55, because it has on board power and reset button. But it is more expensive, maybe about $120. Same G1610. Each 7970 requires 250W if you undervolt.

Thanks, What sort of hashing rate you are getting in this setup? When you say 1250psu+750psu, how you allocated the card? 1st card and mobo on to the 750psu and the remaining 3*7990 into 1250psu??? are you using add2psu or just jumper? have you tried more than 8 on lga1155 or the later lga2011? What you do for the cooling? would be nice to post some pictures of the rig.