Maybe it's a faulty mobo, check for any bulgin or leaking caps. Very strange to fail memtest with a new stick of ram.

OK, I spent most of the week using a different computer while my main machine was running memtest. Some things I learnt along the way that might be of interest:

-faulty RAM will usually fail in test #4, regardless of timings and clocks
-test #5 usually fails because of timing and clock speed issues
-most errors are caught within 10 passes but the latest error I saw was after 57 passes of test #4!

-and most important of all: DON'T BUY CHEAP RAM! It will work fine but it will begin to fail earlier than quality RAM. Even if they are chips from a good manufacturer on a no-name circuit board. This doesn't mean you are getting quality chips from a no-name supplier, it just means you are getting the chips that the original manufacturer sold off after testing. And spending your time with memtest to find out what's going on is not something you want to do.

Bottom line for me is that I had 3 Broken DIMMS, 2 good ones, and a dying GPU. Luckily all the components should be under warranty so the only thing I've wasted is my time.

Phew, this time I managed to finish the post without the artifacts suddenly taking over while I'm typing how everythings fixed.