I've been trawling for a while and can't find an answer sorry. It's probably here somewhere.
I was considering smashing in a GTX 590 or such into my current setup for the release of Battlefield 3, but a mate suggested my e8500 @ 3.16 with 4gig DDR3 might bottleneck?
It's really hard to find info regarding how much CPU power you need to run games these days. Even harder to see if Direct X 11 will up the ante.
The CPU charts on this site have 3d Mark Vantage GPU performance which gives a rough overview I think? But seems to suggest CPU isn't important really at all. The difference between my e8500 CPU and the best fairing is about 3 or 4%.
Is this accurate? Should i just stick with the e8500?
It is likely that you will get performance from a faster CPU especially in Single Thread Games. The better i series processors have Turbo Boost that really helps these games out. Some games will play better than others depending on where they require resource. However a GTX 590 would be of use to you and it would certainly come in to its own when you get around to upgrading your CPU later. The RAM wont cause a bottleneck. 4 GB is more than enough for gaming.
3d Mark Vantage GPU performance test really only tells you about the GPU performance, thats it. Its designed so the CPU wont affect the results much.
Find some benchmarks for other games you plan to play and see if they are restricted by the CPU, many games are only in need of two cores so an E8500 can still hold its own reasonably well, but some, like GTA IV show significant penalties on anything below a triple core CPU. How much you get bottlenecked will depend on the game, but for the most part i would expect there to be a CPU limiting factor for most games with that CPU/GPU combo, a better option would probably be a GTX 570 or a 6970, they wont need quite as high throughput and will leave you some extra money to upgrade your motherboard/cpu down the line.
The reason you can't find a simple answer is that it varies so much between games. Sometimes there will be a huge bottleneck, sometimes there will be none at all. The last game in the series (BC2) was heavily multithreaded and somewhat CPU demanding, so I would think a dual core would definitely hold you back for battlefield 3.