32GB of RAM isn't expensive. If anyone's interested, here's what I'm getting and why:

ASRock 970 E3
Thermaltake TPX-1275 Plat.
G.Skill Ares 32GB RAM
Sempron 145
x2 - Sapphire Vapor-X 7970 6GB

Total $1700

Just 2 GPU's initially, to calculate hash rate and profit potential. I can add a second power supply and 3 more cards if it's worth it. At the least, simply replacing the CPU would make this a decent gaming machine I could sell or use for a racing simulator.

I'll update this thread in a few weeks when it's up and running with both Bitcoin and Litecoin results.

Thanx for the input. One source recommended having as much system ram as total VRAM on the graphics cards. i.e. - with five 6GB 7970's (35 GB ram) I'd want a full 32 GB on the system. Specifically for Litecoin of course. I know Bitcoin isn't ram choked.

I have a 60 GH/s miner coming, and plan to expand with several Terrahash or KnCMiner rigs later this year. Still debating if its worth building a $3000 Litecoin rig.

Building a GPU rig for Litecoin mining.  Does scrypt use the GPU card RAM only, or should I max out on system RAM as well?