Upgrading Computer...Maybe

So...my current computer was pretty much a beast back when I built it, but I haven't upgraded it since. Now, it runs pretty much everything at maximum quality, but it has started to slow down for various reasons.

Specs are:
Intel Core 2 Extreme QX6700 @ 2.66 GHz
3 GB Kingston PC2-5300 DDR2 RAM
250GB 5400rpm Maxtor HDD
2x GeForce nVidia 8800 GTX 768MB
nVidia 680i SLI-compatible Mobo
Running Windows 7 Build 7100 still
Now, I really can't pinpoint why my computer has been slowing down, as I recently reformatted prior to installing the Win7 beta. Most of my games run smoothly enough, but I personally believe I should be getting better performance than I am.

Any ideas on what to replace to get a good boost?

what are you using to measure/benchmark performance?
please don't say windows experience index.

only thing I'd touch on that rig is maybe a faster rpm HDD, if using a 64x system another gig of ram, and update Win 7(if needed, not sure on current build).

if you are wanting bleeding edge, it is gonna cost you, but of course you already know that. if that is the case then, leave that rig alone, save up and start anew. that's how I'd roll. by the time you get done replacing parts, you may as well have just built a new 'puter.

the new i5/7 cpus are looking pretty nice in these eyes.

what performance exactly are you getting in what games? Your setup looks pretty decent, and should be adequate for most games still unless you have a huge resolution (30" LCD Monitor etc...)

Im running the EC of Windows 7 still. Im not using any certified benchmark performance tests, just the frame rate in games. In MW2, for instance, I often get a steady 30 FPS where I believe I should get 60+. In Crysis I barely manage 20FPS. Hell, even in Dawn of War II, I don't know my exact framerate, but I can see the frames getting rather jerky when in combat.

What resolution and settings are you trying to run? Framerate numbers alone are completely useless.

Nothing about your system really jumps out at me; the RAM and hard drive are probably the weakest components, but they shouldn't affect your FPS in games too much. If you really want to upgrade, grab a 5870 to replace your 8800GTXs. You can also try a modest overclock on your CPU/GPUs to see if that improves anything ... I don't know why you'd run an Extreme Edition processor at stock settings, given that its most compelling feature is the unlocked multiplier.

Im running everything off a 22'' 1680x1050 monitor. The cpu is underclocked as I have had issues with it overheating while overclocked.

Are you running the stock heatsink on the CPU, or aftermarket? Temperature shouldn't be a big issue on the Core 2, IIRC.

Assuming you're not running any AA, your numbers do look low. A single 8800GTX should manage ~25 fps in Crysis @1680x1050 with no AA. You might actually be CPU-limited here. How much RAM is your system using with a game running?

Crysis doesn't do all that well with scaling in SLI (basically no scaling in Crossfire for that matter) - I noticed that I got significantly better performance in XP than in Vista with Crysis - I suspect that Win 7 would be the same as vista. In XP I could get low 40's in Vista mid 30s (High settings no AA). I ran CrossfireX with dual 4850s, but it was exactly the same with a single card. (1920x1080). With the right drivers though you should at least match that with SLIed 8800 GTXs.... have you tried any alternative drivers?

I've tried to stick with the latest drivers. So, no, I haven't really tried any alternates. All cooling is stock, with one extra fan near the processor. I'm running 4x AA typically in Crysis. I suppose it makes a big difference. I'm going to try swapping out some of my memory for just some newer sticks. I'll see how this works.

there isn't any GPU that does well with Crysis at 4xAA - turn it off and you should get a HUGE boost in FPS. That right there is your problem (with that game anyway).

if you are using the Aero theme (vista/win 7), drop it. right there you will get a performance increase as well. -just an FYI.

So, I fixed my Crysis problem by lowering the AA to 2x. Thanks for that tip! I then found out something wrong with SLI and some games and decided to turn it off for Guild Wars which helped a ton for some reason. Thanks for all the help, time to start saving the money I was going to spend for a new second system.

Aero is automatically disabled when using fullscreen DirectX applications. Unless you play in windowed mode, enabling or disabling Aero will have no impact on your framerates.

not buying that. alt-tab with aero enabled. it is never set to default/disable to a basic theme, unless the game conflicts with the set-up. not sure what games it disables for you, but the only ones it disables (for me) are the ... reloaded types, if you know what I mean.
-if it does disable itself, it's pretty damn quick to re-enable when I alt-tab.

and even then it usually defaults to a basic theme before the game starts. it's usually accompanied by a little balloon tip from the systray. can't remember the text in it though.

only game that I vaguely remember auto-disabling Aero/Glass was GTAIV. not even sure on that one to be honest.

http://forums.anandtech.com/showthread.php?p=28980910

perhaps "let windows choose what's best for my pu-pu" is keeping it on for me?

/edit2
the only thing I have in my arsenal that disables Aero is, 3dmark06/3dmark vantage. yes, you do see a performance gain in both mem usage and FPS when Aero is disabled, at least I do.