If you're building a 4x ATI6990 rack, take care of the following:
- The ATI 6990 pushes hot air out on the front and the back of the card. If you're using a closed case, make sure you can exhaust all the hot air as this card will also be blowing hot air IN the case. I'm using an open frame.
- I opted to use 2 linked PSUs.
- I also used PCIe risers with an extra 12V rail.
- Make sure your motherboard actually supports 8 GPUs. I had to disable various internal components (USB3 controllers, eSATA, etc...) before it would even start, there were not enough BIOS resources available to start all these things and the 8 GPUs together.
- Ya, I got a bit caught up with that part with the current case, I did not plan ahead too much on the other stream of hot air exiting the card. Not really a problem with the current case, but could be much better. I am thinking of putting the cards flat (long side parralel) to have the air inputs all pointing in the same direction and pipe cold air right there. I also have to make sure the back gets plenty of air.
- I currently have a 1200W PSU, it is plenty for 2 cards, but I have not taken an empirical reading on the actual watts used by the cards and the rest. From reading the specs, I should plan for about ~350W per card (or is it per GPU ?).
- Yes, I am thinking of buying the 1x to 16x adapters with a 12V molex plug in order to not burn out the cable, the cablesaurus ones seem ideal.
- I don't know if this could be an issue, I use a 64-bit linux operating system and a recent motherboard...