"2006 MacPro1,1 upgrade to 3.3Ghz Octo
Mike, I got a couple of Engineering Special 5350's from Ebay for @ $200 per. Worked great at 2.66/1066/266- no problems at all. But I wanted more.
The BSEL mod was easy enough (increasing the FSB from 266MHz->333MHz, to which the CPU clock frequency is tied 10X in engineering samples), but any extra heat at all killed it.
More and more reading, a few failed tries (ok, only one...) and I was successful with a VID mod to 1.4125v.
Now it's stable, so to speak. And as long as my core temps don't go above 65c it's fried gold.
So now I've got 2 Corsair H50's and am modifying the mounting rings to a LGA 771 socket. The first ring looks good and hopefully the 2nd will be ready this weekend with a 4 to 3 pin power molex and extension.
I'll let ya know how it goes.
For the Readers, I've attached pics of the chip mod and current PowerFractal score.
(screenshot trimmed to save space)
Hope to have more for you within a week.
Warmest Regards, Robert C."
BTW - Until someone mentioned it recently, I'd almost forgotten about the ZDnet OC software. Some early reader feedback on it in the June 27th, 2008 news. I also linked that on the Macs/systems page (intel-based Mac section).