Bottlenecked?

Yeah it does sound like a CPU bottleneck in this case. Have you tried OCing the CPU? If you overclock by, say, 500mhz and then play and see what your FPS are, then you'll know if it's a CPU bottleneck.

However, given that your GPU usage isn't that high, also try turning up the details and see if you can get the GPU to run full out.

I have not played BC2 on PC, but I've had some bottlenecking occur in games with my OCed i5 750 paired with 2 OCed 5850s. For example, the STALKER series is not multithreaded so 1 CPU usage is way up around 80% while the others are maybe 20% and with maxed out settings the FPS goes from 50s to 100s depending where I am and what I'm doing, I checked Afterburner and my CPU usage, and when CPU usage was the highest the GPUs would drop their usage a bit because of the bottleneck, causing a FPS drop. In this game, that was especially apparent when going to an area with a lot of NPCs as the CPU needs to load all the info about them so there is short bursts of stuttering/pausing and then it's smooth after they're loaded.

Anyway, in short yes it sounds to me like a CPU bottleneck although not exactly because the CPU isn't overall good enough, but because the game isn't utilizing it well enough. So like I said initally, see if a small CPU overclock will help your FPS and if so, it might be worthwhile to see how fast you can get it.

Going from one quad core 2.66Ghz CPU to another quad core 2.66Ghz and still getting the same frame rates with different GPUs?
That's a hint to me that game is CPU limited.

Sorry......that was a 2.4Ghz to 2.66Ghz CPU swap.

The cpu is running @ 3.2 ghz (both were) and the drop between medium and super high settings on the gfx card as per op was a mere 8-10fps.

My old i7 920 @ 3.8 cranked the game along easily and even my buds hex core amd does (@3.4)

I am thinking that the c2Q is at the end of it's useful life for my gaming if this is the case.
Would a i5 750 do any better or would it be better to roll into a amd hex core?

The i5 750 has an advantage over the C2Q 9450. But you'd need to bump it up above 3.2Ghz also to get any advantage over the swap.
From what i've seen going to the X6's won't improving gaming performance. BF BC2 is CPU limited and seems to respond well to overclocking.
My guess is a Core i5-750 @ 3.8Ghz or above is your best bet.

So it's time to move on from the 775.
The i7 920 kit I sold for the reason that I wasn't getting any benefit from the power.
I was wrong again I guess .

why don't you overclock more ??? bus speed and voltage ??? is you ram limiting you ? or is the board ?

No, my gear is listed in the op and is fine bar the c1 stepping of the cpu.

I won't get much more than another 300 to 400 mhz from that cpu and I doubt it will make much of a difference.
A mate of mine runs a hex core @ 3.4 and bc2 runs sweetly on all 6 cores with a 5870.
My 460 is oc'ed to 900/1800/3900 btw.

I can still get reasonable money if I flog off this 775 gear atm and it will only cost around another 100 to go i5 750 or amd hex.

The 750 is easily capable of 3.8 to 4Ghz.
Blimiing unsure what to do. The whole point of reverting back to 775 was to wait for sandy bridges etc. but I am unable to play a smooth game of bc2. Damned annoying really  

Most people would say that 50FPS would make for great game play.
It almost sounds like you're unsatisfied with the PC's performance just because you know other systems run faster.

Will you enjoy the game more if it's 30% faster?

Thanks for your comments guys.

In regards to your comments wr2, i have run 6 different setups in the last year from e6750 up paired with 585o's and such.
I believe this is nothing more than a nvidia driver issue now.
My cpu is not maxxed out on 4 cores and whether dx9/10/11 aa on low or high, settings on low or high, the gpu is not struggling either.

With 5850's installed, the cpu maxxes out and gpu useage is high. I will havea friend bring around his machine so we can install his ati card to do some final testing with this setup.
I have seen others with 9550's paired with ati 5770 (less powerful card) achieve much better fps.
I will report back in a couple of days.

Again, thanks for the help so far.

I ran MoH beta with similar settings and the gpu is 90% utilised so it's not the comp being cpu bottlenecked but I would suggest simply a driver issue etc for BC2 as per my last post.
Seems that out of 2 games built on the same engine, the beta has better resouce utilization?

I will stick with this C2Q a bit longer yet.

Thanks all.

It's running at 50-55fps, so I don't see what the problem is. Sure, it might be CPU bottlenecked, but that only matters if it is also performing slowly enough for you to notice a significant performance problem.

It might not be drivers so much as bad game optimization. Might be running a lot more CPU intensive stuff than MoH.

Anyway, 50+ FPS is fine, really. It should be fairly smooth.

It might be worthwhile to at least see if other driver versions give better fps in BC2. I don't know about NV drivers but I know ATI released some hotfixes for a few different games like BC2.

It's a bc2/460gtx thing. MoH beta is pretty much just a reskin and it works much better.
Cpu utilization is much more even over all 4 cores and the gpu is 90-% and above in comparison to bc2 which struggles to use 70% of gpu (much less mostly).
50fps might be fine for single player fps'ers but there's no way i would call it good or fine. It stutters etc. Damned awful.

So I am NOT cpu bottlenecked, just bottlenecked by game optimization/drivers.

ERmmm not exactly terrible   50fps is actually quite decent, TF2 is probably the most random frame rate game ever, at a moment i'll have 150fps then jump to 50 and back to 100 or something like that. And as far as my concerns, from that huge jump i notice hardly anything other than my latency issues, stupid 1.5mbps dsl. 50fps is fine.   30 fps is fine, 30 fps is basically when its starting to become noticable.