Sorry, I actually have a 580w G7 power extreme.
Asus P6X58D-E Motherboard, Socket 1366.
Un-branded DDR3 RAM 1333MHz..
2x 250GB seagate hard-drives.
Old card: Powercolor 5670 1GB GDDR3 PCI-E 2.1
New card: VTX Radeon 7850 2GB GDDR5 PCI-E 3.0
I have no access to another system. I am just bewildered as to why it would display first-time, until I reach the desktop, then crash and show no signal onwards. I have removed old drivers. I have restored the BIOS to default via the battery and from the settings itself (using old card). I have seat the card in different ports.
The power supply might be the issue. I had never heard of G7, now I know why.
A multiple rail power supply uses cheap components in parallel to produce more power with a “higher” reliability. The cheap components keep the price down. Because they are in parallel none of the rails feel the full effect of the load, so they are able to rate the power supply higher wattage than it should be.
The problem is that, because they use cheap components they do fail. When they do, the bad rail starts crapping out and the others have to take a greater part of the load, this shortens their lifespan. You as the owner of the power supply now have a failing component, but no clue because it’s still putting out juice.
Bad or spotty power will cause all kinds of havoc in your machine. Check the power supply first. Then see if everything else doesn’t start acting better.