I have an EVGA 512-P3-N871-AR GeForce 9800 GTX+ 512MB 256-bit DDR3 PCI Express 2.0 x16 that I am thinking of replacing. It's a great video card, but I would like to get HDMI, which it doesn't have. My computer specs are in my sig, the PSU is a Corsair 750TX 750w so I should have enough power to upgrade.
I'd like to stick with EVGA, I need to run two DVI monitors at 1920x1080. I do mostly photo and HD video editing, not much gaming(I have an Xbox) and I want to run HDMI from the graphics card to a Sony HDTV at 720p.
I am looking at EVGA 02G-P3-1559-KR GeForce GTX 550 Ti (Fermi) 2GB 192-bit GDDR5 at the top end of my spending scale, maybe the EVGA 01G-P3-1556-KR GeForce GTX 550 Ti (Fermi) FPB 1GB 192-bit GDDR5. At the cheap end, I'm thinking the EVGA 02G-P4-2643-KR GeForce GT 640 2GB 128-bit DDR3.
What do you think? Remember, no gaming, overclocking or anything fancy. Two monitors, HDMI out, photo and video editing. Prices with rebates are pretty good right now, I'd like to take advantage of it.
For your overall purpose, look at getting the most RAM and the fastest (as well as DDR5 if possible), you can get. When pushing resolutions that high (3840 x 1080), you need to have good display buffering which comes in real handy for a lot of tasks you're looking at doing. I don't know what your overall goal is with the display outs, but keep in mind that compatibility of different resolutions is hard to acheive (3840 x 1080 and 1366 x 768 on your TV) if you're trying to do so at the same time. Both cards would suit you fine, but the 550Ti is a more worthy card compared to the 640, which both sell for almost identically anyway.
Believe it or not, the 550Ti and 650 trade blows in many aspects, but the 650 is on average 15%-20% more in cost right now. If power savings are worth it to you, than yeah the premium is what you're paying for the 650 card.
If you're dead-set on Nvidia, I'd break the bank a little bit and go with a 650ti. It'll last you longer and keep you happier. If you're willing to go to the radeon end, they've got the advantage with multi-monitor setups, thus you could spend less.
On an unrelated note, I just sent you a PM about the possibility of buying that 9800 offa you.
I decided to go with the EVGA GT640 dual slot, 2G card. It's a pedestrian card, for sure, but I can upgrade via the EVGA Step Up program if the card doesn't cut it. The Windows Experience was at 7.0 for Graphics with my old 9800GTX+, 7.1 for the GT640 and I can run two digital monitors and a TV via HDMI.