I know to some it'll be a complete waste of thread, but I figured I'd post my findings. I ran a few benchmarks that I already had installed, I would've loved to do more but it would require installing more games, application and bandwidth.
I was pleasantly surprised to see my Early 2008 Mac Pro is still relevant and based on the tests that I compared with other reviewers using the same Graphics Card the scores were either close or better. Based on that there is clearly no CPU bottleneck for benchmarks I ran, there were minor differences but are within a margin of error.
Keep in mind this isn't going to be a 100% accurate representation because each site used different drivers, but I think it gives you a general idea if you're looking to purchase a used Mac Pro.. I only tested Windows 10 performance as there wasn't much else to compare to. PS: The 7950 is crippled on Mac OSX if you have a Mac Pro 3,1 due compatibility issue but it performs acceptably though not as fast as in Windows.
Test Setup
Early 2008 Mac Pro
2 x 2.80 GHz Quad-Core Xeon
10 GB DDR2-800MHz Memory
AMD Radeon HD 7950 3072MB
Windows 10 64-Bit
Latest Catalyst Drivers
Intel Core i7 3960X 6 Core EE @4.70GHz
Sapphire HD 7950 3GB 950/1250 : 3DMark 11 Performance Preset - 7008
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Powercolor HD 7950 3GB 950/1250: 3DMark 11 Performance Preset - 7309
Intel Core i7-5960X 8 Core @ 4.40GHz
Radeon HD 7950 1920x1200 GTA V 2xMSAA - 49FPS/Average
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Radeon HD 7950 1920x1200 GTA V 2xMSAA - 45.92FPS/Average
Intel Core i7 920 4 Core @ 3.80GHz
Radeon HD 7950 800/1250 Heaven 2.0 1920x1200 4xAA - 55FPS
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Radeon HD 7950 800/1250 Heaven 2.0 1920x1200 4xAA - 57.5FPS
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
381 NovaBench Score for Graphics Tests (Total Novabench Score: 1224)
Highest Listed Score NovaBench 7950 on Website
375 NovaBench Score for Graphics Tests
I didn't save screenshots guys, so you'll have to take my word for it
. But honestly very impressed that a 2008 Xeon could handle modern games, every thread I was reading most people said the Processor would be a bottleneck despite the 8 Core but that doesn't appear to be the case at all.
Not sure performance will differ in higher resolutions or different games/benchmarks. But this was what I was able to come out with. So far I'm super happy I spent $400(Canadian) on the Mac Pro + $130 for the 7950.. Although I wouldn't recommend buying a 7950 even a legit Mac one because it won't work correctly on a Mac Pro 3,1. But you should be good with natively supported GTX cards
I was pleasantly surprised to see my Early 2008 Mac Pro is still relevant and based on the tests that I compared with other reviewers using the same Graphics Card the scores were either close or better. Based on that there is clearly no CPU bottleneck for benchmarks I ran, there were minor differences but are within a margin of error.
Keep in mind this isn't going to be a 100% accurate representation because each site used different drivers, but I think it gives you a general idea if you're looking to purchase a used Mac Pro.. I only tested Windows 10 performance as there wasn't much else to compare to. PS: The 7950 is crippled on Mac OSX if you have a Mac Pro 3,1 due compatibility issue but it performs acceptably though not as fast as in Windows.
Test Setup
Early 2008 Mac Pro
2 x 2.80 GHz Quad-Core Xeon
10 GB DDR2-800MHz Memory
AMD Radeon HD 7950 3072MB
Windows 10 64-Bit
Latest Catalyst Drivers
Intel Core i7 3960X 6 Core EE @4.70GHz
Sapphire HD 7950 3GB 950/1250 : 3DMark 11 Performance Preset - 7008
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Powercolor HD 7950 3GB 950/1250: 3DMark 11 Performance Preset - 7309
Intel Core i7-5960X 8 Core @ 4.40GHz
Radeon HD 7950 1920x1200 GTA V 2xMSAA - 49FPS/Average
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Radeon HD 7950 1920x1200 GTA V 2xMSAA - 45.92FPS/Average
Intel Core i7 920 4 Core @ 3.80GHz
Radeon HD 7950 800/1250 Heaven 2.0 1920x1200 4xAA - 55FPS
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
Radeon HD 7950 800/1250 Heaven 2.0 1920x1200 4xAA - 57.5FPS
Mac Pro 2008 Xeon X5642 8 Core @ 2.80GHz
381 NovaBench Score for Graphics Tests (Total Novabench Score: 1224)
Highest Listed Score NovaBench 7950 on Website
375 NovaBench Score for Graphics Tests
I didn't save screenshots guys, so you'll have to take my word for it
Not sure performance will differ in higher resolutions or different games/benchmarks. But this was what I was able to come out with. So far I'm super happy I spent $400(Canadian) on the Mac Pro + $130 for the 7950.. Although I wouldn't recommend buying a 7950 even a legit Mac one because it won't work correctly on a Mac Pro 3,1. But you should be good with natively supported GTX cards