System Stats: Intel C2D E6750 Gigabyte GA-P35C-DS3R EVGA 8800GT Super Clocked Edition 2x 1GB Crucial Ballistix Tracer (4-4-4-12) --Older style Crucial Ballistix (2x LED Columns) 2x 1GB Crucial Ballistix Tracer (4-4-4-12) --New Style, supposed to be worse. (1x LED Column) Background: Built this system last September. Ran some OCZ ram for a while, then got a good deal on the Crucial for maybe $40 for both. Computer has been a champ almost the whole time. It has a few issues running Assassin's Creed, but I think that's more of an 8800GT issue as it was very common among several other machines. Flash forward to recent: So I got my two new sticks of Crucial, put them in the machine. Booted up fine and everything. Gave Memtest86+ a run, got to 24% and then it "passed" me. I was eager to play on it so I was like wtf, whatever and went to play games. After a few hours of playing games I ran into problems. The game (TF2) gave me some error (don't have it available now). Told friend, he said he had the same problem once, and restarted to fix it. No dice for me. So I started Memtest86+ up again, and let it run through the night. I woke up and it had 2 passes, and maybe 5 errors. So I knew something was wrong obviously. Once I got back from work today, I took out the old memory, and ran Memtest86+ again. Ran 3 passes (each pass got to 100%) so everything appeared fine, figured maybe my old ram was bad? Took out the new ram, put the old ram back in (all staying to the original slots they were in the previous day) and ran 3 passes just fine (all the way to 100% again...) So I am kind of confused on whats happening, and decide to throw the new ram in again, while keeping the old ram in. So far it's passed twice in a row, now just got an error. Test: 6 Pass: 2 Failing Address: 0008a8329fc - 2216.1mb good: 00200000 bad: 00000000 err-bits: 00200000 count: 1. So I see two problems. (Semi-Cliffs) 1. Why is MemTest86+ 1.70 only getting to 24% 2. Why is the memory failing before, and not now? (now failing on third pass) --I am pretty sure I seated the ram fine, but that's my only idea of why.