I saw your post earlier, and was meaning to write down specific specs on my work machine today to give you some potential guidelines. But with the very rocky PTS run today, I completely failed to follow through. I also ended up missing all my meetings too
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Your system looks plenty beefy to be honest. Are those i7 Xeons, or older P4 based cores?
The draw calls made into D3D are very CPU intensive. A good chunk of that is due to the lego-like nature of the mechs; being formed out of dozens of individual components rather than a single character that can be rendered with a single draw call, like in most other games. It's also compounded by the particle system, the terrain system, and the older Scaleform 3 integrated into the engine.
Because of this, you're definitely going to want a very strong CPU. I'd recommend a quad core. I have an older i7 920 at home which does decently well; and I work on an i7 of some newer flavour at work. You'll want a very fast bus to your GPU for efficient main memory to GPU DMA transfers, so PCI x16 or better. If your current Xeons are net burst cores, making the move to i7 based cores would definitely be the most important thing you can do for performance.
Fast main memory, and low latency if you can manage it; especially if we get that high-res 4k texture pack released. I think I run 8/8/8/24 at home, but it's been a few years since I specced the system.
Because we're so CPU limited, most decent GPU's will do a good job, but the more raw fill rate you have, the less the particle system will slow you down. I run a 1GB AMD 5870 at home. Pretty sure I have an nVidia card of some flavour at work, although I'll double check on that for you.
SSD will help load times somewhat, and may also reduce hitching if an asset didn't pre cache correctly. I doubt it would make a difference for general framerate in-game.
Hope that helps!