I'm thinking (not positive, don't know all your settings here) that either lowering your base clock or reducing your PCI and/or memory speed a tad more (which is affected when raising the base clock) should eliminate/reduce the screen flickering. Not sure but that's where I would start. Are you running a dedicated graphics card, if so which one (or more) and what is your PSU make and model (could be a factor here).
Memory speed: 1448 (181 x 21), therefore underclocked from default of 1600
PCI express is set at 100% I believe, in the Gigabyte bios.
PSU: Antec Earthwatts 650w
I played BF3 for awhile without issues, but yes those stress tests like IBT - Maximum, OCCT - Large data set, Prime 95-small fft were making the monitor turn off and then come back on either a few seconds later or perhaps 30 seconds later. It would happen more than once, for example near the end of each test loop in IBT testing. That kind of tells me the PSU might be strained?
Perhaps not enough amps on the 12v rails, I don't know.
Unless the PSU is faulty (it's possible), you shouldn't be even coming close to stressing it, the PSU shouldn't be an issue (could be bad though so...). I'd say bring the PCIe lane down to 75%, possibly a little lower. Try again.
Sorry it took so long to reply