So far it's been rock solid with the 160x25, and memory is 1280mhz or something like that, which is fine because triple channel and whatever. Maybe 166x25 will get it to run at 1333 which is what's rated to be at.
When I was overclocking my X5650's, I had a higher BCLK than multi... I believe it was something like 200 on the 'FSB' BCLK and then whatever multi... I'll dig out the Screen shot....
I never really played about with it so much but I don't think I had the best of Xeon's for overclocking, but then I don't think the 48GB of RAM I had in the system helped either... Which is why I swapped it out for 24GB which was again still too high really.. At the time I didn't have 2GB sticks and only 4GB ones which came with the SR-2...
If I ever get around to it again, I'll see if I can get the beast fired up and see if I can figure out a few overclocks
It does have in it a pair of X5675's now... I think it's about time we saw if the thing worked still!! lol