Upgrading ATI HD 4850

[quirk]

Hi there,
this is my system I bought in 2009. My graphic card causes performance issues and occasionally nasty flickers in demanding games (I guess due to hardware defect). Also the GPU fan failed once and got replaced. Long story short: I need to replace that GPU!

APPROXIMATE PURCHASE DATE: next 2-3 weeks (aka. not urgent) BUDGET RANGE: 100-125 Euro (Germany) (resp. 135-165 USD)

USAGE FROM MOST TO LEAST IMPORTANT: mainly 2d indie games, Dota2, recently Batman: Arkham City

CURRENT GPU AND POWER SUPPLY:
GPU: ATI Radeon HD 4850
PSU: be quiet Dark P. Pro 750W

OTHER RELEVANT SYSTEM SPECS:
CPU: Intel Core 2 Quad Q8200 2.33GHz LGA 775
MB: GigaByte EP35-DS4 -> Specs
RAM: 4GB of Corsair DDR2-800 Ram XMS2-6400 -CL 5-5-5-18 in Dual Channel (upgrade to 8 GB worthwhile?)

PARTS PREFERENCES: Don't care whether AMD/ATI or Nvidia

OVERCLOCKING: I don't overclock. I originally intended to upgrade to Crossfire when buying the system, but I ended up with a single card.

MONITOR RESOLUTION: 1920x1080

ADDITIONAL COMMENTS:
Besides playing games, I use the system for less demanding stuff like browsing, video, etc., but yet for programming/compiling.
I do not have the obligation playing on max. details.

I'm curious about your suggestions,

 

[trumpeter1994]

I'd probably suggest a Radeon 7850, it would push the budget a little bit but heres one for $165 and another for $160 after rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150642
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161426
I have a system that is around the age of yours, I run a Core 2 quad q9300, with 8GB of DDR2-1066, The RAM is something I'd put to question, It's gonna cost you a lot to upgrade to 8GB probably because it's DDR2, I spent ~$120 on my RAM just to get 8GB of this stuff. How much longer do you plan on using this PC?

 

[quirk]

The Radeon 7850 looks quite promising, though it's a bit pricey at my place. But the performance boost is great. What'd be the next cheaper & reasonable option(s)?

Regarding the RAM: Buying now the same 4GB kit would cost $55 (used, ebay). I'm planning to use this PC for atleast one full year.