New to forums (hey) so don't give me to much flack if this question is in the wrong section.
I've been wanting a gaming desktop for a while and my friend recently gave me his XPS 420 for free (Score!)
To be able to play most current games i understand its GPU is going to need a upgrade and i have already decided on a GTX660 (non Ti). All i want to do is be able to play current games (like upcoming GTA V) in mid-high setting at a moderate resolution.
Q6600 Core 2 quad @ 2.4ghz
3GB of DDR2
ATI Radeon HD 2400 PRO
Windows 7 64Bit (not OEM)
PSU: 425W Dell (other threads say that Dell underrate their PSU's)
1) Personal knowledge unable to answer that. Sorry
2) Your CPU will be a bottleneck not to the performance of the GPU, but more to the game. If it is not proportionally as powerful it will limit the performance of your game.
3) Yes, as long as your motherboard can support the new GPU.
4) I'd recommend upgrading the RAM to at least 6 GB to ensure good performance (and also since you're running 64-bit). RAM sticks are pretty cheap these days and the minimum for even normal computer work would be 4GB.