Is it a CPU bottleneck?

[TNGL]

Specs:
Q6600 (I believe) @ 2.4Ghz
4GB OCZ DDR2 @ 800Mhz
An old mATX Gigabyte motherboard (can't give you the exact product, until I've had a look on the motherboard for it's name).
EVGA GTX 480 1.5GB
OCZ 700W

Recently my brother's upgraded his GPU and PSU, however the graphics card is really under performing, with usage only hitting around 85% (if you're pushing the graphics card, with high in-game settings) and only 65% with lower settings. I'm pretty sure the CPU is bottlenecking it, as I read that when you lower the settings, more work is given to the CPU. To further this, in BF3 he could play on Ultra and get 30 - 40fps, high and get 45fps, medium, 45fps etc...

If you think the CPU (and the ram, motherboard etc) is bottlenecking it, what's the cheapest CPU, ram and motherboard to buy that would be able to remove this bottleneck? He doesn't mind going second hand, so the member's market is an option should anything suitably cheap appears.

 

[TNGL]

Q6600 at stock is definitely a bottleneck.
Cheapest i5 1155 and board with DDR3 RAM you can get would remove it.

Thanks for that. Could you also confirm that those GPU usage figures and behaviour corresponds with a CPU bottleneck? Or is that unrelated?

 

[TNGL]

So, this, this and this would remove the bottleneck? I have to be sure, as it wouldn't be my money I'd be spending, it'd be his.

You seem quite knowledgeable, is there any other alternative you could think of to save money? E.g. sell the GTX 480 and downgrade to a card that won't be bottlenecked by the CPU, will run at 100% and can run BF3 on high settings.

 

[TNGL]

have you tried overclocking the current CPU?

Not yet, and I'm not in a position to do so at the moment as it's using a stock cooler with current temps not too great.

 

[TNGL]

For saving money you could go second hand on 1366 stuff, can get 920's for sub 100.

This is what I was thinking. My 930 runs fine, but it would appear that the 1366 boards cost considerably more than the 1155 boards.

 

[TNGL]

You can get some cheap 1366 boards, there's been some decent 60 quid boards.

An ASRock P55 and an i5 750 wouldn't suffice would it?

 

[TNGL]

Update:
Tested the GTX 480 in my X58 setup and it worked flawlessly.