Hello, Im not very PC Savvy but i have an ok knowledge. The current pc i have is ok but not the best. I have decided to sell my xbox as i rarely play it and im putting it towards money that i have saved to upgrade this PC.
I would keep the motherboard and processor and just upgrade the video card to a GIGABYTE GV-R787OC-2GD Radeon HD 7870 GHz Edition 2GB 256-bit GDDR5. Here in the US it is $239.99 and a good upgrade from your card.
Due to your motherboard getting damaged I suggest you also buy a ASRock 970 EXTREME3 AM3+. This motherboard will work with your Athlon X4 CPU and your RAM. It works with the newest 8 core piledriver CPUs. Buy this first to see if your problems goes away. If they dont buy an 8GB ddr3 1600 RAM kit for around $39. If this doesn't fix the problem then you may have damaged the CPU as well. Any AMD X4 or higher will work. Once you have removed the source of the acting weird. Do note tho the video card could have been damaged. If you have any way to test the video card would help. If you cant then you may have to flip a coin on the cpu and video card fix. I suggest these last because the are less likely to be the cause than the motherboard but more costly than the RAM.