I've been running my EX490 for about a year with pretty much no issues. I had updated the server to 4GB of RAM and WHS 2011 with DrivePool.
I bought an E8600 from eBay recently and finally got around to installing it last night. The installation was a breeze but upon first boot I received an alert from DrivePool that my 2nd disk was missing. Disk Management showed the drive present but as RAW instead of NTFS. Moving the drive to slot 4 allowed the disk to be recognized as formatted with NTFS. Putting a new disk into slot 2 and formatting it worked fine so I'm not sure what that was all about but I decided to just leave the system with the faster proc.
Being paranoid about temperature, I left the server running with RDP open and Core Temp open. I came back to the server about an hour later and noticed that my eSATA enclosure had only 1 drive light on (which usually indicates some issue with the host system). Checking the RDP session I had open, I discovered that the whole system locked up and the only thing I could do was power the server off and turn it back on again. At the time the system froze, Core Temp showed the temperatures for both cores to be around 64 degrees C which I believe is OK.
After rebooting the server worked fine for a little while then locked up twice more before I decided to put the stock Celeron back in. After putting the Celeron back the server has been stable and I am able to put the drive back to slot 2 without issue.
I checked the server Event Log but I didn't see anything that would indicate what the issue could be. Do you guys have any thoughts/pointers?
Thanks!