I bought a Quad in December and I am on my 3rd round of RAM from OWC. Are their any known issues with RAM compatibility and the Quad G5? I initially bought 4 GB's in 1 GB DIMM configs. I left the 2 256 chips in there and added the 4 gig chips. My machine went crazy, fan blowing really loud, audio very choppy, video not playing. I ran the hardware tester and it came up showing a bad chip. I sent the pair back. The machine works fine with the first 2 1 gig chips. I got a replacement pair and put them in and the same screwy things happened. I thought it was possibly the slots so I took out the original 512 (2 256 pair) out and replaced them with the newer chips, same thing. So now I am sending them back and waiting for a replacement. Anyone know of any issues like this? Is it possibly my machine? Thanks.