Hi guys, I have an Asrock G31m-s for the old LGA 775.
I know the motherboard PSU itselfs makes the monitor flicker on and off constantly for some time until it fixes itself most of the time when I turn the monitor off and on constantly, or strangely enough, when I open Firefox as the flicker continues, and once Firefox loads, the flickering stops immediately for it.
I have trie 3 different video cards, with the same proble, and different VGA, DVI cables, as well as going directly off the VGA of the mohterboard itself, but same thing happens.
I also flashed the latest BIOS for it, as well as tried older versions to no avail.
The solution was very simple... a really old power supply unit that was really really cheap causes wonders like this and more... and being so cheap, it didn't even have a led to show light codes (even old ones from 2005 have those).
This was a 2006 machine that I mistreated really badly maintenance wise, and bought already assembled really cheap, so now I'm surprised the PSU lasted this long anyways.
Got a cheap CX430 for only 25 bucks off Microcenter after rebate (sweet). It's a more than OK PSU for an old machine like this. I recommend Johnnyguru's review of that PSU, but above all..
If building your own machine... NEVER, ever go cheap on the PSU, and never base its quality only on wattage... the amount of amps on the +12V rail, the 80 plus certification, and even the soldering inside, and the brand of capacitors it has, seem to be better guides as to its real quality, and power output, NOT wattage alone.