Upgrading PC component for 5870

You should be fine with your CPU,you can OC it always too but most games are GPU limited so you will be fine.
About the RAM,what is your current RAM ?

Your PSU is fine. Just don't OC everything and install a bunch of drives. The recommended minimun power requirements are 500W and 40A.

Your CPU will be fine. Every system has "bottlenecks" and you can't get around that. But your Q8300 will have less of a bottleneck than lets say an older dual core Core2 would have.

4gb ddr2 800mhz

how much faster is q8300 than e7400?

On review, 5870 usually way too fast as i7

The e7300 is 2.8GHz and the Q8300 is 2.5Ghz. speed isn't always a factor. If the app is multi threaded and takes advantage of 4 cores, the Q8300 will have a big advantage. If the app is not, the speed of the e7300 will have a slight advantage. The e7300 also has 3MB of L2 cache, and the Q8300 has 4MB which might have a light impact.

I'm not sure what you are asking about with the i7 comment.

+1^
Q8300 is a very good CPU,a 2.5GHZ Quad can handle games fine and you can always OC it too  

5870 will not bottleneck any current CPU.

^ is that a question or statement?

statement, it might be possible to be true

Do you mean a 5870 will not bottleneck any current CPU or do you mean no current CPU will bottleneck a 5870. Video cards perform the output to the monitor, and does not feed the CPU (at least without software). Therefore a video card is not going to bottleneck a CPU. However, a CPU will bottleneck a video card. The faster the CPU can process the data the quicker it can get to the video card creating less of a bottleneck. The whole bottleneck argument it completely overused because EVERYTHING is bottlenecked in a PC by something else, it just depends on how large those bottlenecks are.

5870 will not bottleneck any current CPU

That's false,please read some reviews,old CPUs like P4's bottleneck a card like HD 5870 in some games,also please read what other say and then reply.
Since you have gotten your answer, i will close this thread before anything worse happens