AMD processor for Fluent
 

Hello.
I want to upgrade my old PC. I do not have a large budget, so I wanted to do it at the lowest cost.
Now I have 2x2GB 1333 DDR3 and AMD Phenom II 955 BE. I'm thinking about to buying an AMD FX series processor (not quite sure which) and to buy 2x8GB DDR3 1600. I'm not entirely sure if that 1333-1600 combination will be good. Maybe there will be better to sell old RAM and buy more 1600 chips in the future?
Another doubt is about processor - which AMD will be good in reasonable price? Or maybe Intel - in corresponding price - is better?
Now I have 8 core Fluent 15 license and I'm working on VOF simulation of laser welding process. All comments and suggestions are welcome :)
Best regards!

CFD performance is typically limited by memory bandwidth. So go for max number of memory lanes and RAM frequency. Forget your old 1333 MHz RAM. I dont know of AMD processors. But if I had 8 cores to utilize with a tight budget I would go for a two machine cluster of Intel Core i7-4820K (this will give you 2x4 memory lanes of 1866 MHz, 8 memory modules DDR3 are required). CPU cost: 2 x 320$. If budget allows the most efficient machine for 8 cores will probably be a Dual CPU Xeon E5-2637 v3 (this will give you 2x4 memory lanes of 2133 MHz, 8 memory modules DDR4 are required). CPU cost: 2 x 1015$ .