So, I guess you can read my system specs below. I'm not wanting to seriously upgrade for awhile. At least not an expensive one. I've been thinking about upgrading my two 8800 GTX's to a new single graphics card, but I'm wondering how much of a performance gain I'll get without doing the whole thing (i.e. motherboard, cpu and such). I have been shying away since newer cards are 2.0 PCI Express, and my motherboard is only 1.0, so I figured I might not be getting much of a boost. Any comments would be appreciated.

PCIe 2.1/2.0 Cards are backwards compatible with PCIe 1.0/1.1 Slots,

The only difference between 1.x and 2.x slots is Bus Bandwidth and Bus voltages w/ a few extra features.

I know plenty of people that have 58xx Series ATI cards on PCe1.x Slots. You lose 1-3% Performance off the cards overall performance due to some PCIe2 Interface features being disabled.
I doubt any single Chip Card maxes out the 2.0 Bus Bandwidth and maybe the 1.1 Bus Bandwidth.

A Single 560 ti Would add 128 more Cuda Cores, 384 Cores vs your 128x2 8800GTX, The 5xx Series Fermi core is also tons more efficient.
Add 256MB of memory (well you’d technically lose 512mb since you got 2 8800GTXs in SLI), But the New Memory is GDDR5 vs GDDR3 So 4000 Mhz vs 1800MHz x2 (3600MHz effective)
Subtract one 8800GTX Running at 60^C and Taking up 2-3 Slots.
Subtract the Power Draw of 2 Cards and Add the power Draw of one ( I think 2 8800GTX Cards use more power than a Single 560 ti, I’ll have to double check).
Subtract an SLI Incompatibilities and SLI Scaling issues.
Remove Support for Windows 95, 98, ME, 2k.

The 8800 was superceded by the 280. That was passed by the 480. That was passed and they now have the 580 which has been out for about a year now. So, your cards are due for Medicare and SS checks at this point.

The important thing is your PSU. How powerful is it? If you go to Newegg and look at the cards' descriptions there is usually under specs a line about "minimum 500W/550W/600W power supply recommended" in there. I know when I got my GTX260 I had to get a new PSU because my old one couldn't cut it. Of course having SLI means you were using more than I was with my 8800GTS.


The Jedi Master

I agree with SZ. It's not absolutely necessary, but it wouldn't hurt either if you want more performance w/ less

My 112 Shader G80 640mb 8800 GTS still plows along just fine at Med.-High Settings

In what? At what resolution? That's a bit of a nebulous statement.
My 5850 handles my 1280x1024 max resolution great in most games w/4x FSAA, but some I have to lower to 2x. Also when I get my 1920x1080 monitor I expect to see a performance degradation in most games less than 3 yrs old...and Crysis!


The Jedi Master

My ACER LCD is 1680x1050.

I Run 2XFSAA Max, some games have it disabled for compatibility reasons.

At Stock Firmware Settings of 576 / 900 / 1350,

Of the More recent games: (Im not gonna count old games or games on Xbox 360)
Thirdwire's Strike Fighters 2 Series – Max Details
Thirdwire's Strike Fighters 1 Series – Max Details
Crysis (Windows XP/DX9 - MAX)
Cities XL 2011 – Max Details
America's Army 2.8.5 – Max Details
America's Army 3.5 (Beta) – Max Details
BattleField Play4Free – Max Details
LO:MAC – Max Details (I think I turned a few things off)
DCS Black Shark – Custom Settings (around Med-High)
DCS A:10 – Same, Some things are maxed while others are Med or OFF

My Brothers 5830 chews through everything.....

lol! I actually gave my old one to one of my roommates (he just pieced together a pc just to get by). I was actually surprised at how well it did with a few current games (mostly console ports).

Thanks for the replies. That's just the kind of information I was looking for. I hadn't done too much research myself, but just had this feeling that if I wanted a new card, I should upgrade the motherboard first, but I guess that's not completely true. My PSU should be able to take it, it's an 850w Thermaltake modular one. I'll have to look around and see what kind of deals I might be able to get.

I think you would get a nice performance increase, even going to a 480 which are pretty cheap today.