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WOW Cataclysm has brought not just a new gameplay - it adds much better graphics features. But as a consequence, it raised minimum system requirements and recommended configurations significantly. New DX11 features requires more than just a basic computer with no discrete videocard. The days when about any computer could run WOW to some extent, it becomes more of a system hogger than before are no more. Presenting below is the best configuration today to run WOW Cataclysm.
There are many new options today when it comes to choosing WOW computer configuration.
Beggining from the lowest, or minimum recommended setup. It most often consists of an AMD processor like Athlon II X2 or X3 clocked above 3.0GHz either stock or overclocked. You will be needing at least 2GB RAM but 4GB is much preferred, there is a big difference. Videocard - could be Nvidia GT 220, better with DDR3 RAM, or GT 240 GDDR5 or GT 430 which is a bit slower but newer and has some really fancy features. Packed in a case with good cooling with reliable PSU at least 485W - should be reliable brand. Hard drive space, DVD speed do not matter much. Motherboard - if you can choose - get 785G chipset, it's cheap and reliable, but still it is just fast enough.
Moving on to playing WOW Cataclysm in better than just medium settings you will be needing extra firepower on your arsenal. We suggest at minimum the AMD Phenom II X4 or Intel Core i5 Quad processors. Together respectively with AMD 880g/870/890 series motherboards or P55 for Intel. 4GB RAM is still enough, though RAM goes down in price and you can surely get 8GB or more - if you want, it's not mandatory for most games. Video card - here you have many choices. Starting from Nvidia GTS 250 and 450 and ATI Radeon 5670, 5750, 5770 cards are all super for WOW on High settings. Older 9800GT will be still good too, same as ATI 4670 1GB DDR3 which can still pack a punch.
If you can spare more cash - upgrade CPU to the top AMD Phenom II X4 like 955 or 965, and Intel CPU to Core i7 based on sockets 1156 or 1366, the latter is much better. It will give very nice level up for WOW in 25 man raids in many areas - WOW is CPU dependent and every MHz you can spare is of great assistance here.
As for the video cards - if you want that computer for more than just WOW look for the mos popular cards today - Nvidia GTX 460 and ATI 6850 and 6870. All 3 can play WOW on Ultra and will have no hassle in any other game or application. All 3 are the hits of the season and preferred by all major PC benchmarking websites.
Cheapest WOW Cataclysm optimized PC would play you around $800 if you want it on med-high settings. Better price range is around $900-1200, and above that it will be a insanely cool already.
Please be informed that these suggestions are based on real world game play experience, not some synthetic benchmarks or Blizzard recommendations. Fundamentally, what you have to do is keep RAM at 4GB at all times (or above), CPU - Phenom II or Intel Core i5 Quad and above, and video cards at minimum GTS 250 or ATI 5750 and above. These setups will keep things tight in all raids and instances, not disappointing you when you need those FPS the most.
AMD systems are more economical though, but Intel seems to be a bit more optimized for WOW giving same performance benefits as the price premium - proportional. So it is not really important which platform to get. Just spare some cash as much as you can in CPU (first) video card (second) and RAM (third priority). Don't forget about motherboard chipset too, as well as case and PSU quality, CPU and overall cooling - that helps alot even with slower CPUs.