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Hi guys,

Need a bit of advice as I can't really find a lot of information on these online.

What is the maximum number of MSI Radeon HD 7990's I can use on one set up using the 6-rig guide here? http://www.coinminingrigs.com/how-to-build-a-6-gpu-mining-rig/

I have read that using 2 750w PSUs is suffitiant for running 2 7990's. I have not seen anyone using more than 2 7990's and an extra lower powered GPU. For example, the Rocky Mountain miner are using this same setup, 2 7990 and one smaller one so it seems this is the safest way.

Anyone know what MB and PSU they are using?

Thanks,

This is probably not much help to you but I've just started mining with a MSi 7990 and at first I thought I would try and get away with my current 700W PSU but no chance, as soon as it got anywhere near full mining speed it would shutdown. I've just installed a 850W and all is good although I'm having serious heat issues at the moment.

I can't run the card anywhere near full speed as I can't keep it cool. Been trying various intensity's in CGminer but it seems to be either half speed or full speed no matter what flags I use, would be nice If I could get it running at around 2/3 of it's max :/

I am running 4XMSI7990 without problem on Gigabyte GA-Z68AP-D3 ATX Intel Z68 Express DDR3.

I use two OCZ 1250W Gold power supply, which is too high for 4X 7990.

If I run 3X 7990, one 1250W PSU is OK as I undervolt, the power consumption is less than 400W each card.

My setting: 1.0V VDD, core/mem 950/1000MHz. When it runs at 1.2V, the power consumption is much higher than 400W, maybe 550W each card.

The temperature varies due to the quality of thermal paste application on the GPU.

Running more but smaller PSU's is cheaper.

I think the standard setup is 750W PSU for Mobo with 1 GPU and then a 350W PSU for every GPU you add after that.

Keeping a spare 750W PSU and a spare 350W PSU is cheaper than keeping one spare 1100W PSU.

Great to hear someone successfully running these beauties in a 4x setup! Your 1V 950/1000 config sounds very similar to mine. One GPU always crashes at 1V 950MhZ for me, though, so I have to run at a lower 920MHz. I can absolutely confirm the power draw is smaller than 400W, I'm running 2x7990 on a Akasa Venom Power 1000W Gold PSU without any problems. Regarding temps, the GPUs run at roughly 57,60,63,72C, but I've got to admit my current setup is very hacky: built inside an opened case, but with 6x fans mounted around the cards.

I'm really curious how you keep your cards cool? Do you have the normal open miner approach with powered PCIe risers? Do you do anything else, e.g. remove some of the shields around the card?
What temps are you getting? If you re-applied thermal paste, how much did it improve your temps?

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.

Thanks for your reply, I very much appreciate it. You've got a lot of hashpower there! Probably about 20Mh/s - I'm just bumbling around at 3.5MH/s.

I might look into reapplying the thermal paste when I have time and the coin craze calms down a bit. Even 2-5 degrees are worth it, particularly if I get 5 degrees less on the hottest GPU. I've also tested the limits a bit on my cards - one card is great and seems to go up to 1000/1000 on 1.02V, but the other cannot cope as well and crashes above 960/1000. I do like to keep my cards cool <72C, so I'm sticking with lower settings. It's all great fun.

Pls. make some photos (http://imageshack.us/) of 7990 rigs!

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

We have 4 UD7 MB's running 3 7990's each.  We have 4 Hercules 1600w PSU and 4 OCZ 1250w PSU powering each unit with everything, MB's, fans, cards, etc.

From personal experience, even though you can do two 750w PSUs, I'd go bigger just to protect yourself.  The 7990's are power hungry and we blew out a few PSUs in that range with them.  Get a good brand PSU and with a lot of wattage.  Personally I'd never get another Seasonic PSU again.  They were awful and wouldn't last more than 10-15 minutes without dying.

We did a lot of testing with trial and error to come up with this setup.  The 7990's are great cards but you will need some heavy duty PSUs to keep them happy and make sure you keep them cool.  They will heat up wherever you put them with the quickness.

7990 is terrible for mining. Overpriced and major heat dissipation issues. Dont bother getting into to the game with anything less than the new r9 series, they are way cooler and a bit more efficient than the venerable 7950.

Online prices are OK, and people successfully mine on 7990 (https://bitcointalk.org/index.php?topic=351742.msg3984495#msg3984495).

he buy all 7990, when see to sell  (https://bitcointalk.org/index.php?topic=186282.msg1930010#msg1930010)

They could be had for a while at a great price working out cheaper than a 7950 per core. Undervolted and slightly underclocked they can produce 630kh/s per core at 70C - 75C for under 400W. No complaints here.

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. 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

+1

I got mines cheap and they perform.

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.

For the GA-Z68AP-D3, I used two PCIE16 slots and PCIE1_1 and PCIE1_3. PCIE1_1 does not need jumper.  PCIE1_3 needs A1B17 jumper. I use PCIE riser for the PCIE16_2, no jumper needed.


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.

Can you please make some pictures (http://imageshack.us/) if this rigs?

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.

The additional cost of 7990s pay for themselves after about 6 months, possibly even quicker now with the rise.  After that the income per watt is much higher than 7970s/280x.  Most people that knock it are too quick to do their math and only look at instant ROI.  Mining is a long term game, it makes more sense to think ahead.  Unless you have unlimited power at your disposal.

Most homes come with 200amp service, at least around my current area.  Given you have to leave at least half of that for appliances, etc., Getting the most bang you can per watt can be a very big deal.  Of course personally when I move I'll be ordering a larger transformer.  :D

For those that got their 7990s for $699 a few months ago, that is the steal of a lifetime.  I am looking forward to the 2x290x cards that should be around the corner.  Could be near 2,000kh/s per card.  

Here are images of my rigs, both with 4X7990

When I use 750W+1250W, I use the 750W to drive the MB, 1X7990 and powered risers. The 1250W is used for 3X7990. I only use jump to short the green(?) to ground.

In this setup, you need to use the Afterburner to reduce the voltage.

The hash rate is about 5.1-5.2MH/s, depending on the exact clock speed. I usually use <1V for Vcore. Some good cards can run 950MHz, but some can only run 916MHz. For the 950MHz card, the hash is 660kH/s. The memory speed is 1000MHz.

I use some extra fan for cooling if the cards are in a PC case.


The MB is Gigabyte GA-Z68AP-D3

http://imageshack.com/a/img585/5536/jilr.jpg



The MB is Asus P8P67 work station.

http://imageshack.com/a/img802/6306/xlr7.jpg

You can check my Rig, I was able to run 4x 7990 @ 950/1500MHz 1.05V = TOTAL 1650W, or @ 900/1500MHz 1.025V = 1500W.

http://www.youtube.com/watch?v=MIuoLd8aaas

My Mining Monster Rig Review: http://[Suspicious link removed]/W7hGim
Cryptocoin Mining Profitability 2014: http://[Suspicious link removed]/lffJKq

Performance (depending on the clock/voltage):

CPU Usage: 55% (average)
RAM Usage: 1.9-2.2GB
Hash Rate: 4800-5600KH/s
Power Input:  1740-1970W
Power Output: 1500-1800W
Temperature: 58-79'C

Specifications:

Mobo: ASUS M5A99X EVO R2.0
CPU: AMD Sempron 145 (Single Core 2.8GHz)
Memory: Corsair Vengeance 8GB DDR3 1600
GFX: 4x MSI Radeon HD 7990 (8 GPUs)
PSU: Cooler Master Silent Pro M2 1500W
SSD: Kingston 60GB SSDNow V300
Cooling: Sinbo 18inch Floor Fan (75W)


Software:

Microsoft Windows 8.1 (64-bit)
AMD Catalyst 13.12
AMD APP SDK 2.9
CGMiner 3.7.2

Settings:

GPU Voltage: 1.050V (1.100V)
GPU Clock: 950MHz (1000MHz)
CGMiner 3.7.2: -l 13 -g 2 --thread-concurrency 8192

Windows 8.1 and 8GPU's
http://www.firstever.eu/wp-content/uploads/2014/01/5MH-Server.jpg

Mining Pool and 5MH/s+
http://www.firstever.eu/wp-content/uploads/2014/01/5MH-Pool.jpg

For the core frequency you are using, there is little difference in performance if you use 1000,1200 or 1500MHz memory frequency. You may save more energy by using 1000MHz.

guys... just tried to put 4 7900 into on rig - failed. I use 1-16 powered risers, two PSU 1250 and 1000w. My win7 sees only 6 GPUs, one of them work on low memclock/gpu regardless of MSI afteburner settings. I tried various slots on my MB ASrock FM2A88X Extreme6+ - same results. Any ideas?

I use Win8 for my rig using several version of Catalyst>=13.4. Maybe you can try that.

Or you can use mod version of catalyst.
7xGPU + Windows // modding AMD video driver is the answer?
https://litecointalk.org/index.php?topic=11761.0;topicseen

Thank you, Eastwind - Win8 helped! Now I see all GPUs, thought the problem might be with one of pci-e slots. Still have a trouble with a low hashrate on one gpu, but I think I will resolve it.