Ubuntu 12.04 2+ GPU hanging
I'm trying to set up my rig according to epixoip's guide from the wiki (HOWTO: Ubuntu Server + AMD Catalyst + oclHashcat). I got it up and running on one R9 290 all right, 160-170 kh/s as advertised. But then I got a few problems - would be extremely thankful for someone helping me out as I've been bashing my head over this for the last 12 hours and it hurts.

I got six R9 290 and two PSU 1250 W each. I am trying to get running at least two of GPUs with one PSU (should be more than enough). Mobo is MSI Z77 (3x PCIE-16 + 4x PCIE-1). GPUs are 100% identical and I'm confident about them and other components.

I have no problem with one card in a PCIE slot - boots and works. However, when I take it out and attach to a riser (tried two different) it doesn't provide any video signal. I'm not sure if it does anything because it doesn't look like BIOS is loading at all (no signal, Ctrl+Alt+Del does nothing). It just hangs in a powered on state without output.

Once again, if I put the same card into PCIE-16, without a riser, it works like it should. Tried a few risers and slots for them, no luck. I'm not missing anything? Should I do something extra for risers to work?

Then I have tried putting two cards into PCIE - they boot okay but only into Windows 8 (on another drive I got). But I can't get them working in Ubuntu 12.04, it freezes upon boot, obviously when X tries to start. Once I remove one card it works okay. And if I put one card on a riser and another into PCIE even Windows won't boot - the same problem as above, no video output, no BIOS logo. Nothing.

Any idea why risers don't work and/or why Ubuntu freezes when I put on both cards?
you are probably using bad risers. If you are using x1 risers only you need to connect/fuse some contacts on the x16 slot. (don't ask me which ones)
yep, sounds like bad/low quality risers.
Thanks guys for dropping by.

Quote:If you are using x1 risers only you need to connect/fuse some contacts on the x16 slot. (don't ask me which ones)
I know that I'd need to short circuit 1x but I am trying to use 16x risers and the seller told me they were previously used okay. I will see if I can get more to test out.

What about Ubuntu freezing upon startup? This is my main problem so far. I have tried Fedora and Debian for those 12 hours and they did not even play with either Catalyst 13.x/14.x (too recent kernel?) or oclHashcat 1.21 (Debian doesn't run it due to GCC version). There are numerous patches online but I wanted to avoid them and Ubuntu looked like a perfect way to go as explained by epixoip. But it only works with one card for me Sad (now just want to repeat that Windows 8 works just fine with the same setup so it must be software)
I have made it through. Indeed, some risers turned out to be bad and were messing up the entire thing. I managed to get all 6 cards running under Windows 8.1 + Catalyst 3.12 + hashcat 1.01 (later Catalyst didn't want to start up; I also didn't WindowsUpdate) and under Ubuntu 12.04 using epixoip's wiki page. Windows setup was quite easy, just install the OS, then install Catalyst and then all GPUs are detected with no problem. Ubuntu was also fine given the wiki page (it's worth noting that after changing GPU configuration - number, slots, etc. - one should reboot into single user mode and mount -o remount,rw / && amdconfig --adapter=all --initial -f - otherwise X will hang; Windows does that automatically).

Then I've set up VNC server with x11vnc - it's better than others because it captures X framebuffer directly instead of creating new X session which eliminates configuration of OpenCL running under VNC's session (I couldn't easily do this with tightvnc, for example). Given epixoip's autologin setup it becomes essentially a standalone headless box.

Also, I discovered that my screen didn't like DVI input from any of the Sapphires (resolution above 1200 would be all messy) so I had to use HDMI.