After my GeiL uLL PC6400 broke down, two sticks at once(!!) I picked up Crucial Ballistix PC6400 4x1GB 4-4-4-12 sticks from an ebay guy in the US. Very cheap, sealed brand new and they work like a dream till now. No problems with them at all and they overclock easy. After reading this I get a bit worried lol
So a lot of people are still RMA'ing these? 

