My 5x 750 ti rig is giving me huge headaches. I'm running all 5 on powered risers and 6 pin connectors on a 750W RM corsair PSU. Asrock h81 btc pro mobo. 8gb RAM. Latest Nvidia drivers.

Is anyone getting huge lag/computer freezes when running multiple 750 Tis (5+) in one instance? I'm running windows 8.1 64 bit, and starting up all 5 at once freezes the PC (sometimes it's huge lag, sometimes I need to reboot, sometimes cudaminer crashes). Seems to only work with regular scrypt without freezing/crashing 100% of the time. I get 250 khs/card mining LTC at stock. I'm about to switch to Windows 7 to see if that changes anything.

If i don't use autotune, TDP usage seems to be pretty low (~850 khs for 5 cards), config: -l T5x24 -C 1 -H 0 -i 0
W/ autotune, I get low 80% TDP. 99% GPU usage.

Also any bit of OC to my cards (EVGA 750 ti ftw) seems to crash cudaminer about 10+ mins later (even "low" ones of +20 core, +200 mem). I don't know how other people seem to get huge clocks with these cards..

Any help would be greatly appreciated. Will throw 10 VTC anyone who can get me up and running stable at ~300+khs/card... Feel free to PM. Thanks!