Running MSI Radeon HD 7990's

[Gazza1]

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.  

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.  

[Eastwind]

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





The MB is Asus P8P67 work station.

[Marcinprv]

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

[Eastwind]

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.

[dzzima]

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?

[Eastwind]

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

[dzzima]

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.