k1114 :
I'd suggest using a gpu renderer anyways, it'll save lots of time. But you should tell us what you are using. Or better yet, fill this out. http://www.tomshardware.com/forum/353572-31-build-upgrade-advice
Approximate Purchase Date: e.g.: tomorrow or in 2 days
Budget Range: $1500
System Usage from Most to Least Important: 3d modeling, light gaming
Are you buying a monitor: Not for now
Parts to Upgrade: Processor, Motherboard, GPU, RAM
Do you need to buy OS: No
Preferred Website(s) for Parts: newegg.com or amazon
Overclocking: Maybe (not now though)
SLI or Crossfire: Maybe (in the future, not now)
Your Monitor Resolution: 1440x900 or higher
And Most Importantly, Why Are You Upgrading: for smooth 3d modeling and rendering
thank you.