Well I had mine at 245x11=2695Mhz for a few weeks and everything was fine but when I tried to play CoH it was crashing. Every other game was fine.
I dropped it back to 250x10.5=2625Mhz and everything runs fine now.
I think I've got it running at 1.5v. It idles at 32C and gets to around 48C under full load. This setup has really impressed me. I got higher temps running at 2500Mhz at stock voltage in my previous case. This P180B has made quite a difference in my OC.