To me this sounds like a PC or video card issue. That's also a very power hungry GPU so you need to talk to the PC maker about the PSU and more. I've seen folk have to fit 750 to 1000 Watt PSUs to drive those.
I feel for folk in this position since they often find there is little support for gaming PCs they made themselves or integrated on their own.
I have a few days ago received this monitor from OCuk.
Samsung S23A750D 23" 120Hz
I am using it with a Gainward Nvidia GTX570 Phantom GPU via DisplayPort cabling.
The trouble I am having is that the monitor has great trouble picking up a signal from the GPU when the computer has gone into sleep mode or been switched off (at this point I can get a signal to the monitor). It's only when I turn the computer back on and then the monitor that I get no signal. To get a signal I have to remove the power cable and put back in or sometimes remove the DP cable and put back in.
I have tried not turning the monitor off (the monitor goes into a sleep mode when the computer goes into sleep mode) but on putting the computer on it does not pick up a signal.
It is only by removing the power cable and/or DisplayPort cable will I get a signal. And this is intermittent.
I have tried upgrading the firmware from Samsung but this hasn't helped.