The expected arrival date on my eBay X5690 is August 22, fml.
What!?! That's almost 2 months away! Wasn't there a quicker option?
[doublepost=1561689564][/doublepost]Just did a few Geekbench and Cinebench comparisons between a few of the single CPU Xeons in a 5,1 (flashed 4,1).
X5650 (2.66ghz x 6 cores)
Cost: $9
Single Core: 2732
Multi Core: 13315
Cinebench R20: 1396
https://browser.geekbench.com/v4/cpu/13617775
X5677 (3.46ghz x 4 cores)
Cost: $15
Single Core: 3262
Multi Core: 11829
Cinebench R20: 1167
https://browser.geekbench.com/v4/cpu/13693564
X5675 (3.06ghz x 6 cores)
Cost: $25
Single Core: 3050
Multi Core: 14323
Cinebench R20: 1540
https://browser.geekbench.com/v4/cpu/13694487
The only better CPUs for the 4,1 and 5,1 Mac Pro are the X5680 and X5690... which are at least double or quadruple the price vs what I've benchmarked. I'll leave it up to the end user to decide if its worth a few hundred points on Geekbench or Cinebench vs the cost of the X5680/X5690.
EDIT: Just purchased a X5680 for testing... here are the results:
X5680 (3.33ghz x 6 cores)
Cost: $45
Single Core: 3152
Multi Core: 15143
Cinebench: 1681
https://browser.geekbench.com/v4/cpu/13853778
Looking at it on paper, it would seem the higher base clock would result in a measurable performance gain. However, in both benchmarks (done multiple times, the highest scores are listed), the X5680 only gained around a 6% improvement (and only a 3% improvement in single core scores). Perhaps this is because the X5675 turbo boost at a higher rate (+400mhz, totaling 3.46ghz) than the X5680 (+270mhz totaling 3.60ghz). Either way, for a nearly 100% increase in price, I cannot really recommend purchasing a X5680 over the X5675. 3.06ghz seems to be the sweet spot for these 4,1/5,1 Mac Pros.