How much is my CPU bottlenecking my graphics card?

so I have a amd athlon 64 X2 5000+ (oc'd to 3 ghz) and 4gb of ddr2 ram and im running windows 7 home premium, I had a radeon hd 3870 (512mb) before and was fairly happy with the performance, but needed a upgrade badly and so I decided to get a radeon hd 6570 (2048mb) yesterday and most games seem to have 50-75% more FPS but some games have very erratic frame rates, sometimes at 30fps and then jump to 60+fps in a instant. and some games like crysis 2 are actually working worse on the 6570 then on the 3870, go figure?! :bang:

PS:

my cpu is dual core obviously, I realize that this videocard was designed to be used with a quad core cpu...I just want to know how much It will cause it too suffer, and why certain games like (bioshock, bioshock 2, crysis 2) actually got worse fps, crysis 2 was getting 30+ avg fps on the 3870 and on the 6570 same settings its getting 20+ fps avg

 

The card you upgraded to is not a fast one, nor was designed to better run with quad core CPUs. The rest of the system is slow for today's standards and this affects gaming performance, but not in a "bottleneck" way. It is just slower than it would be in a modern PC.

If you face FPS jumps from 30 to 60 in some games, you might want check if vsync is enabled and disable it. If you run some modern games under DX11 mode (not available for the 3870), they tax the card beyond its capabilities and will run quite slow.

The 6570 is a modern low end card, while the 3870 an old high end card. It is not surprising if you see cases where the latter performs better. And BTW, those 2GB RAM on the 6570 are pretty worthless, if this card cost you more than its 1GB version.

 

Is it DDR5 or 3?

Use this to compare there specs:

http://www.gpureview.com/show_cards.php?card1=653&card2=547

 

I agree with this post

 

No cpu bottleneck.. i had that cpu long time ago and it bottlenecked my 8800GT which is about twice as fast as your card.. so you should be fine.