Hi ToonArmy,

Here is the official system requirements for the HD 4850 graphics card. Note the power requirement. You should be OK with your existing PSU, however you will be running fairly near its maximum rating with very little room, if any, for further system expansion. I suggest that you upgrade your PSU to at least 650 Watts.

(Note: Because this is an image, if you wish to follow the link in green, you will need to type the address manually.)

I ran that card - MSI R4850 - just fine with a 400W Fortron Zen fanless PSU albeit with a low power AMD 4850e (no relation!) processor. PSU got a little warm but no problems.

My guess is your old PSU will be fine.

Cheers guys it arrived today! Very happy with the performance so far tested on Crysis Warhead and PES2009 Demo. How do I check the temperature of the card? I used Everest Ultimate Edition to check for my old 8600GT but it doesn't show for my new card.

EDIT: Also both PES2008 and the PES2009 demo are crashing when running in windowed mode. I never had this problem before. Anyone know how to fix this?

in catalyst control center there is overclocking area at the bottom of the app that shows you the temp or you can just download gpuz
GPU-Z Video card GPU Information Utility

for all the running info on your card

does it happen when running in full screen mode too? if not then it may just be a driver issue that has yet to be resolved.

there are alot of fixes in 8.9 that were causing me problems in 8.8 so be sure thats what you want to do before you do it the 8.9 drivers are a lot better too an fix some of the Anti ailiasing problems i have running dx 10 games running it in full screen mode is the prefered option for most games to it may be that the game just doesn't like it that much also you could look for updates to your game which can resolve alot of issues too.

glad to have been able to help