Screen blinking for no reason

[realmatrix]

Its been 3 months rma'ed cards back and forth..yet I am unable to resolve the issue.
Trouble is I can't really find whats wrong.
All of a sudden for no reason (no matter what am I doing surfing,watching movies..or just idle) the screen blinks (like when installing the display drivers for the first time) for about a second or two and then comes back up.At times it may not even occur.

At first I thought the cable was at fault..I replaced the vga cable yet it resurfaced.
There is no such behavior from the onboard display..hence I thought the card was at fault
I rma'ed it twice.
Later I upgraded my card from xfx 9800 gt to xfx 4850 xxx edition.
Yet even after using two different chipsets the problem remains.

Now for the sake of troubleshooting what else could be faulty..here..

1)gpu is overheating...thats not the case ..it idles at 45c and goes upto 65 max

1) the monitor..but it works fine from onboard display..so can't really say that's the culprit

2) the psu...assuming the psu was faulty..it would have been much severe case coz there is no bsod,freezing,restarts which could suggest its at fault.

3) I have changed 3 gfx cards..so can't really say this third one is faulty.

Now the only doubt remains that

All this while I am using a pci 2.0 card on a 1.0 motherboard..but I have seen many using it flawlessly and that shouldn't really be a problem.

I am using an antec EA 430 whereas the recommended PSU is 450 but in reality my system is never using more than 315 watts ( as per antec's psu calculator with 30% capacitor ageing)The psu is 10 months old.

Other than the above said issue..everything works fine..so I can't really figure whats
causing the screen to go blank for a few seconds and come back up

 

[Epitaph64]

I had this exact same problem before, and it turned out to be the monitor. Something like one of the capacitors was leaking, and it would lose charge, and have to re power itself back up. My monitor too worked fine in BIOS and if I turned the res/refresh down. But at native res/refresh rate, it would exhibit that problem. You can try turning down the resolution to see if the monitor is stable, to see if perhaps that's the case.

 

[DeFex]

see what happens if you turn the brightness down on the monitor. if the speed of the switching changes then its the monitor.

 

[Epitaph64]

It could be that or the horizontal frequency regulator. If it gets too out of whack, the monitor will restart.

 

[realmatrix]

The monitor is not restarting its just going blank for a second .
The screen blinks only when I have the graphic card plugged irrespective of its resolution.
(The native resolution of the TV is 1360X768)
While using the onboard display..there is no blinking to suggest the lcd is indeed at fault.

Should I wait a while and change the motherboard..after which the only thing left will be the PSU.

 

[chipstien]

I am gonna agree with the others and say it is the monitor. I recently had one of mine go out... it would just go black and then come back on for no apparent reason. if you have another monitor that you can swap out with for a week then do it.