Ok so this is my system.
Memory: Kingston ValueRAM 2GB DDR3 1333MHz CL9
MotherBoard: ASRock 790GX Pro
Processor: AMD Athlon II X3 445 3.10GHz skt AM3
The problem I'm having is this: random crashes that spray artifacts all over my desktop, they look like memory artifacts. I'm running Win 7 by the way. Some other symptoms are jerky audio, like it has a lag and this happens when I'm watching movies to, the audio seems to stop and start very fast. I'm using the on board display adapter and sharing the Ram. I haven't run MemTest on it, I haven't had the time since this is the only PC in the house. If it wasn't for the the crashes I'd think that I didn't have enough Ram since when I check the task manager I usually have about 7mb memory free. When the crashers occur I'm usually running VM Virtual Box, Opera with 20 tabs open and watching a movie, but it has also happened when I was only watching movies in 720p. The CPU usage is also usually very high around 60-80% I don't know if that's relevant. Why I also suspect my motherboard might be at fault is that the first two ram slots don't read the RAM, they did in the beginning, but one day my pc wouldn't start until I moved the RAM to the other two slots on my mobo.
Memtest is easy to run; one of my motherboards came with it in the bios file. Try each stick one at a time in a slot that works. If a stick is bad, you'll see errors right away. You'll have to do some troubleshooting yourself. I would not touch the cpu or any other components without an esd strap; you can ground yourself against metal, but the strap works better and cost about 1-$2 at some outlets.
Don't see your power supply listed; either the resolution is set too high for your video (card or onboard), or the power supply may be too weak for the video. What is your video card and power supply brand and model number?