"Upgrading a 2006 Mac Pro With Dual Overclocked Quad-Core Xeons, Radeon HD 5770, Intel SSD 320
I just received a 2006 Mac Pro as a gift. I wanted to upgrade it without spending a fortune, so Here's what I did:
I bought myself a pair of quad-core Xeon L5320's for $80 to replace the stock dual-core 2.66GHz 5150's. The L5320 runs at 1.86GHz on a 1066MHz FSB - It's a low voltage version of the E5320. I wasn't about to give up 800MHz in order to go quad-core, so I did the BSEL mod to bring the FSB up to 1333MHz and the CPU speed to 2.33GHz, netting me a loss of only 333MHz in exchange for twice the core count.
My CPU's are labeled SLAEP, indicating that they are G0 stepping as opposed to the earlier B3 stepping CPU's which have the SPEC codes SLAC9 and SLA4Q. When the G0 stepping came out, enthusiasts were noticing they they ran cooler and overclocked higher on lower voltages than the older stepping.
My L5320's run stable at 2.33GHz at their low default voltage. I have not found any other reports of attempts to BSEL mod the L5320's without raising the voltage. Of course, "About this Mac" reports them as 2x 1.86GHz unknown (patch for that linked in some older reports IIRC), Intel's MacCPUID correctly reports them as running at 2.33GHz. They run really cool too. During an 8-thread Prime95 torture test, the CPU Heatsink temperature never exceeded 41°C and no single CPU core ever exceeded 57°C. This was in 90°F heat in my apartment without air conditioning.
2.33GHz is a very conservative overclock for G0-stepping Clovertowns. I actually wanted to buy E5330's or E5340's, which BSEL mod to 2.66 or 3.0GHz, but they're expensive and hard to find, because they only exist as engineering samples (I noticed a report on your site (see macs page) by someone who got a set of x5350's up to 3.33GHz with water cooling and a voltage mod. He has a youtube clip of MacCPUID showing his CPU's as the older stepping. I wonder if Intel produced any of these with the new stepping and, if they did, whether you'd be able to get them to that speed with standard cooling and default voltage.)
I bought a 160GB intel SSD 320 because I've had good luck in the past with intel SSD's. I installed it in the 2nd optical drive bay with a 2.5" to 5.25" adapter and connected it to one of the unused optical drive SATA ports with a right angle SATA cable. The system feels incredibly responsive. I also was able to enable TRIM in Lion with TRIM Enabler 1.2. My Xbench score is attached.
I have a new radeon HD 5770. As everyone has been saying, it works on even the oldest Mac Pro's, mine being no exception. I'll do some more testing and follow up with you.