the thing is the monitors are fine. and the gpu supports both cards at once, just not when actually in windows explorer. its wierd
If the entire rig isn't shutting down, then it might not be the PSU. Unless you're right on the ragged edge of how much power is needed vs. how much you're actually supplying. Sounds awfully like a monitor problem, especially if its intermittent--Ant's not far off that it may be the cables. Are the cords bent badly? Might be shorting out, hence the flicker. .... maybe it is the refresh rate?