Hi guys, I have a problem which I’m hoping your experience and knowledge can help me with. I hope this is the correct place to post - feel free to move it if not. The problem itself seems trivial but I believe it could be highly significant. Let me start with the actual issue I have now, then I’ll go into the background. The Problem: Prime95 blend test appears to freeze on the first test, but no errors are shown and I can stop the test and close the program with no problems. Other Facts: The system is all at stock speeds and is stable for Prime95 small FFT test, Windows, PS, DW and gaming (CoD2). I have no issues with running this PC from day to day, but I want to overclock it again but don’t feel that this is sensible until I know that everything has a clean bill of health. Memtest runs for hours on end with no problems, using pretty much any combination of latencies (within reason! ). The CPU is brand new, fitted yesterday and Primed on Small FFTs overnight. CPU temp was stable at 46-47 degrees without the CPU cooler fan running at all. I had this problem with my old CPU (which I believed was the problem) and hoped it would be fixed now. The History I bought the majority of the PC components earlier this year, tested everything and then overclocked it up to 2.66Ghz (295x9), RAM @ 590Mhz 2.5-4-4-8. It was stable and fast and CPU temp was <50 degrees on load. After some time, I started having stability issues so clocked it all back. I could no longer get the PC to boot using CAS 2.5, although it was fine using CAS 1.5 or CAS 2. Overclocking was out of the question, with reasonably modest clocks causing windows to not boot. Clearly, my first concern was that there was a problem with the RAM, but after some extensive memtesting, I concluded that the RAM was fine (memtest has been run overnight, then the CAS frequency changed, then run again overnight….). The next thing to look at was the CPU memory controller; hence I bought a new CPU. I’m now concerned that it’s the motherboard. If this is the case, I need to try to somehow prove this so that I can RMA it with justification. With the PC working fine from day to day, I don’t see how I can do this. Maybe I’m being a numpty and it’s something really silly like a Windows service or a piece of software, but I have formatted and it didn’t help any. Any help is much appreciated!!!