Sorry wrong about the board, its a "Giggle Bite"; but it is not a power supply issue, except for the possibility that you don't have the power to the card connected properly, (I think they have more than 2 wires in their power plugs, but I'd have to take my machine apart to look). Power supplies have nothing to do with IRQs and memory conflicts. (NOTE : I am also using a Giggle Bite board with a Power Colour Radeon 4850 1 Gig PCI Express card, so the setup should be similar).
Depending on what kind of plug is on your monitor cord, if you have one of the old 15 pin plugs, as opposed to one of the newer ones, (See photo below)
Then I would reccommend that you get ahold of an old PCI video card, (Pick one up for about $4.00), and install it in one of your PCI slots, and hook your monitor up to it to install "Windopes". Once you have Windopes up and running we can figure out what the conflicts are.
And here are the IRQs that my machine, (Intel Q6600 2.4 GHz Quadcore, on a "Giggle Bite" board, with a "Power Colour Radeon 4850 w/ 1 Gig Memory" is running :
I think yours should be able to run pretty much the same IRQs. They are both "Giggle Bite" boards, and both "1 Gig Power Colour PCI Express Cards". So if all else fails you could try resetting your IRQs to see if that resolves that problem.