Hi
I am banging my head against this problem for a while
I have Sapphire 7970 Ghz Edition Vapor-X
and Powercolor PCS+ Vortex II 7970
Each card mines fine on its own. However if I put two of them into my motherboard (GA990XA-UD3) only Sapphire is recognized.
Funny enough it does not matter which of the two PCIe slots it is in, always Sapphire is seen, not PCS+
Both cards spin fans. I tried a crossfire bridge, but no success. I am putting them into the 16x and 8x slot, so both are running at 8x and it is detected by gpu-z (this is how the mobo works - it is 16x for one card, 2x 8x for two).
I have also tried 1x to 16x riser for one of the card with second in the 16x slot and again, does not matter where, Sapphire is recognized.
That is both Windows and Linux can only see this card and so is cgminer.
I flashed motherboard bios to latest version.
I have latest drivers on Linux and Win. Though I think the other card should at least be seen by the system.
I have only 650W power supply (which itself is a high efficiency one - can output up to 54A of 12V - up to 648W), but I lowered voltage on the CPU and I think when the cards are just booting, they should boot up fine and be recognized and only at full load there may be a problem with throttling.

Thanks!

Any help is appreciated and there is small bounty for successful advice. (I am thinking about 0.2 btc - I am a late btc adopter and I did not manage to become filthy rich yet

I thought I am knowledgable about computers, but this is getting ridiculous

Simple idea: since there are many intelligent people in this crowd, I bet many of you are curious about stuff in the subject.

Biotechnology and genomics is a new cool thing and you can see many reports in media about it. What is common to those reports is lack of depth. Also biological knowledge has exploded, especially recently, so it is hard to grasp what is it all about without specialised knowledge.

I want to answer your questions and keep this thread interesting and entertaining. Fun to read, that's the main goal.

I am working in the lab, I am a graduate student and have been doing molecular biology research since 2002. I am an enthusiast of the topic, so my knowledge is sufficiently broad, I think.

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The answers are for free. However I accept donations, since grad students are not paid so well...
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