The Phenom 9950 BE is a first generation Phenom processor that uses the AM2+ socket, there is no Phenom II 995 yet, however the Phenom II's are a refined architecture with a size shrink so they perform better, and run cooler.
Because the 9950 is an AM2+ processor it will only work on AM2 or AM2+ boards which use DDR2 ram, it does not have a DDR3 memory controller integrated into it so it is not possible to run it on a board with DDR3 ram.
If you are buying your parts now i really suggest going for one of the newer Phenom II's they will be significantly faster and provide you far more options.
XP is not the restriction on RAM, a 32 bit OS can only support 4GB of addressing space, some of which is used by various components on the motherboard leaving only about 3.2GB of address space remaining, this limit applies to all 32 bit OS's not just XP 32 bit. A 64 bit OS can address far more memory than you can get your hands on today, so if you are running XP 64-bit it does support more than 3GB of RAM, but if you are going to buy a new OS go for 7 over XP.
Thanks .. for the lead ... so the question arises ... is there a Phenom model that can/shall support DDR3 Architecture? I just dont want to fall back, coz here in India DDR3 is just penetrating and withing 6 months DDR2 shall be obsolete.
And as for Windows 7 ... hope it is not another Vista repeated.
The Phenom II's and Athlon II's are the only AMD processor that support DDR3. DDR2 is not obsolete, it will be around for quite some time yet, probably atleast another year or two in the US. There is no performance boost going from DDR2 to DDR3, just better upgrade options and a price premium.
7 is a significantly improved version of vista, i have yet to encounter any issues with it.
A Phenom II x4 925/945/955 depending on your budget, and if you plan to run 2 cards get a 790X board from Asus or Gigabyte, if you only plan to run a single card a 785G board will save you a bit, it doesnt matter which one of them you get it from as they both make good stable boards.
What resolution are you going to be gaming at? Higher resolutions will require a stronger GPU which will take a good chunk out of the budget. Also make sure you get a good PSU, im not sure whats available over there but for a single GPU you need a good 500 or 550(~40A), for two GPUs you need a good 700-750W PSU(~60A), try to get one from Seasonic, PC Power & Cooling, Antec, Corsair or OCZ if they are available over there, if not Thermaltake, Enermax, and Coolermaster all make good units as well.
Just to check quick to make sure Intel wouldnt be a better value, how does the price of a Phenom II 955 compare to an i5 750?
The MA790FXT uses the 790FX chipset which allows for 16x/16x crossfire or 8x/8x/8x/8x quadfire, the 790GPT uses the 790GX chipset which is identical to the 790X chipset used on the MA790XT except that it has an integrated video chipset, they both provide 8x/8x crossfire, the 1(x16), 1(x8) means that one of the slots will only ever act as an 8x slot even if you only have 1 GPU plugged into that slot.
The performance difference between a GPU in 16x slot vs an 8x slot is negligible with single GPU cards, only dual GPU cards like the 4850x2, 4870x2, GTX295, 5970 would receive any bottlenecking from the slot so the lane configuration isnt something you really need to be concerned about.
The HD3300 is incredibly low level if you plan to game, but is sufficient for HD video playback and office work, the SidePort memory significantly boosts its performance over those that dont.
I would go for either the GA-MA790XT or the 790GTP depend on your needs, the 790FX isnt really useful for the average person, they should be priced similarly so pick whichever one has a slot configuration that will work best, if you plan to move 2 PCI cards over then its important to find one that would allow them to fit.