Hey everyone first off thank you very much for reading this post and for any advice you have to bring to the table. I am currently thinking it is time to upgrade my GPU it has been almost 3 years since I built this system. If I am fine for my GPU feel free to tell me but upgrading GPU every three years is something I normally do. My budget is around the 350$ mark and I plan to have it power 3 displays a 27" Asus Display port monitor and 2x 24" Asus Monitors with HDMI and DVI on them. Preferably the card would be able to use Diplay-Port for the 27" and HDMI for all the 24" and since it is using a p7p55d-e using SLI or Crossfire isn't the best idea to my knowledge do the the limitations of turning the power down to 8x on each card.
Currently I am using a home built PC with specs:
Ram: 2x2 Corsair 1600
Motherboard: Asus P7P55D-E PRO
HDD1: Intel 80g SSD
HHD2: 500g Samsung
GPU: XFX Radeon HD 5870 2g
PS: 650W Corsair
Either one would be a huge upgrade for you. They are very comparable in performance to one another; don't get too caught up in trying to compare the tech specs directly, look at some actual benchmarks to get an idea.
Some people just have a preference / loyalty to nvidia or AMD/Ati GPUs. I am partial to nvidia personally. If you have no particular leanings, the 7970 GHz edition is probably a slightly better buy for out of the box performance.
Completely different architectures. It all depends on the throughput of each component. Comparing the these two cars is like comparing a Viper to a Lamborghini.
Anyway, I would advise the HD 7970 for one simple reason, VRAM. You very wisely got the 2GB version of the HD 5870 three years ago, and you want to make the wise decision with this card too. Also the Radeon can be overclocked by 20% or so, and it has 50% more memory bandwidth. I think it will definitely last you longer than the GTX 670.