Well im also looking for 3d rendering and multi tasking-production. My gpu is hd6770 oced 1gb vram and ill be getting a mobo with 2 pci express slots. I have 9 gb of ram.
I know games dont make use of multi cores very well, but im also thinking of system longevety because while its kindof a beefy system I will eventualy build a gaming rig andthis will become a family rig. I was just wondering If the 1100gt is enough of an upgrade over the 1090gt to warant a purchase
If you're already overclocking, then you really only need the 1090T. Although the 1100T is only $10 more last time I checked, so it really isn't that drastic of a decision. Getting a six-core may not help your system longevity very much. When games get around to even using that many cores, the chip will probably be considered slow. For rendering and heavy multi-tasking, the extra cores can come in handy.
And 9GB of RAM? That is an odd number to have, which makes me wonder if you ended up disabling dual-channel with whatever configuration of sticks you have. 8GB, or 2x4GB sticks, is plenty enough already.