can you guys help me out ? I have a new 6gpu 750ti rig. Butt windows 8.1 only installs 4 gpu's i managed to installed the 5th gpu manually. I tried installing the 6th gpu manually butt then it says this driver is not suitable for windows vista :S this is weird because its windows 8.1 enterprise.
my mainboard is the asrock h81 pro btc.
I have 6x 750ti running on win7 x64.
Didn't use anything different... just the regular driver download from NVIDIA.
My advice is to put 4 cards in and get them up and running. Then shut everything down and add one card at a time. Let windows do all the discovery and it takes a few minutes as it sits there and searches, but after a while it seems to finish and say 'your hardware is ready to use'.
Once you get the 5th card installed, reboot and make sure it is working fine (couple more boot ups and start mining), then add #6 and let it discover again.
I have only had to do it twice, but I do remember having to do a few reboots to get everything installed, but never had to really mess with it.
I am also using the ASROCK H81 BTC.
Good luck, hope this works for you.