Advice needed on upgrading prebuilt system

[openML]

Hello guys, new to system building and never upgraded my computers so I need your help. I bought my PC prebuilt at a store with monitor and everything included, so they saved on some of the components. The system is going to be 3yo next month and my warranty expires. Since opening my case would void the warranty I have no idea what PSU i got(max400w) the memory i think was Nanya or something @667MHz and the case is a very basic, one fan on the back setup.
So... I've decided to ask you guys what should I upgrade first, both quality and performance wise, aftermarket cooler, better case, better quality PSU and RAM... I'm quite happy with the performance since I play with no AA and at 1680x1050 so most of the games run 40-60fps on high settings, although it runs a bit hot. Some of the games I play for reference: Mass Effect 1/2, Dragon Age, The Witcher, Rome TW, Grid, NFS Shift, F1 2010. For some reason Shift 2 and The Witcher 2 run at 13fps.

And my sys:
Windows XP
Motherboard Gigabyte GA-G31M-S2L
CPU Intel Core 2 Quad Q6600 (stock @2.4GHz, stock cooler)
GPU Xpert Vision ATI HD4850
HDD Toshiba 2x500GB
ODD LG DVD-RW
Monitor Acer P221W LCD
Keyboard Logitech Wave 450
Mouse Genius Netscroll Optical
Speakers Logitech LS21
Memory 4GB(3 with my XP)
PSU
Case

p.s. plan to buy my next system in 2-3 years,
and thanks

 

[mortonww]

prebuilts are tricky. I would suggest getting a new cooler like the Cooler Master Hyper 212+, overclocking the Q6600 and adding a Radeon 6850

but......the case likely won't accommodate such a tall heatsink, so you would have to buy a new case. But if you're okay with that, I would suggest a HAF 912($60), a Radeon 6850($130 this weekend, $160 otherwise), and Cooler Master Hyper 212+ ($30)

Looks like the gigabyte board in your prebuilt is a standard microATX, so you should be fine switching cases. The CPU cooler is so you can overclock the Q6600 a bit to alleviate some of the bottlenecking of the 6850. This depends on your motherboard allowing you to overclock, which I'm not sure it will.

 

[openML]

That was pretty much what I was thinking, and thanks for choosing brands available in my region (SE Europe) here only the HAF 912 Plus is available and there is 20$ difference to the 922 and 690 II Advanced so they may be a better deal. The 6850 will probably need better PSU as well. 212+ here is 50$ and 6850 is 200$, not fair man Thanks for the quick reply and one more question: if I invest in better case, what are the chances that in 3 years time it will be compatible with the MBs?

 

[mortonww]

Well, the ATX standard has been around for quite a long time. I doubt they would need to change the screw patterns or size of the motherboard any time soon (especially with the trend of moving so many features onto the CPU itself), so you should be able to carry that case over to your next build.

I wondered about the power supply, but a system with a 6850 in it uses about 280 watts during full load:

http://www.guru3d.com/article/radeon-hd-6850-6870-review/10

which is pretty similar to their numbers for a 4850

http://www.guru3d.com/article/amd-ati-radeon-hd-4850-review-force-3d--powercolor/7


So you might be okay.

 

[openML]

So I read the articles and both in the GPU manual and tests it's recomended 450W+ PSU. Also, the criteria for unsuficient power:
bad 3D performance
crashing games
spontaneous reset or imminent shutdown of the PC
freezes during gameplay
...so guess what, all of that happens to me on some games(NFS Shift and Carbon). Guess I need a new PSU now. Checked the manuals of 690 II advanced, HAF 922, Scout and Elite430 and it turns out the 912 Plus has the most spacious interior and is the best value, not sure about the design
So thanks again for the links and the great advice, much appreciated.

 

[mortonww]

Something like this would be perfect:
Corsair Builder Series CX600 V2 ($50 after rebate)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139028