Mac Pro 1.1 cpu upgrade

I have a 2006 MP 1.1 with two dual xeon 2.66 (5150) I have been told that because I have the first logic board (not ending in x7q) that I can't go to 8 cores because the LB won't support them. Is there much for me to gain by going to dual 5355 s, or would my processing speed be about the same ? Thx

2006 mac pro CPU upgrade: where can i get... - MacRumors Forums

this guy didnt seem to have a problem in 2009. Id do some more searching and reading if I was you but seems like you should be fine.

Never heard that one before about the logic board. Best priced Quad Core update seems to be the Intel X5355 which run about the $100 mark each. It may be wise to hang off for a while as it is anticipated the next OS release, Mountain Lion, will run on 64bit machines only. Mac Pro 1.1 and 2.1 models are 64bit architecture, but have 32bit EFI Firmware and it is believed these machine will be excluded from further operating system upgrades.


http://www.ebay.com/itm/MATCHED-PAI...965?pt=CPUs&hash=item589370528d#ht_872wt_1165

Thanks for the info. Apparently MP 1.1 was first equipped with a logic board for which no 8 core upgrade was ever available. The second and most common board was upgradeable. I have the first version unfortunately. This is why my source thought going to 8 on my machine would be unsuccessful. The serial for the board that supports 8 ends in x7q , mine does not. If this is groundless I'd be happy to hear it. Thanks again for your help,