I've recently, well not really that recent, bought an EVGA GTX 680 around about 2 months ago, and have been playing on it ever since. And, I recently just noticed that my frames a second have DRASTICALLY decreased when I initially bought the card. To prove this, I watched a World of Tanks replay that I had, when I first bought the card, and played a game on it.

When you watch a WoT replay, it shows you the frames a second you had when you first played it, and the frames you currently have now. I used to have 90-120 frames, on MAX settings, and now I have about 45-60. When I come into an urban area, I range between 30-40, on the same settings. I'd play a desert match, and have about 100 frames ON AVERAGE, and now I have about 60 frames average. I thought it was just WoT, but then I noticed the same thing in War Thunder. I remember getting 150-200 fps on the max settings, and it'd be in the purple\orange colour section, in a game, and now I'm getting about 55-60. It's the same with SWTOR and Battlefield 4.

I've been using EVGA Precision X to monitor my graphics card, and used the Razer Gamebooster application to try and increase my performance for my card. I've uninstalled a lot of things, and re installed others. None of this is making it better. In fact, I think it might be making it worse. I've even taken the card out of its socket, unscrewed the screws, and opened the bloody thing to see if there's a fault there. I'm not sure if this would help, but I used to keep my GTX 640 in with my GTX 680, and just recently taken it out. I'm not sure if that effected the performance of my card, but if it did, I'll put it back in.

I have a Lenovo K430, and only two modifications; The PSU, which is a Corsair CX600M, and the EVGA GTX 2GB 680.

Could someone please help me out? This has been really depressing me over the last couple of days. I've spent at least around about £1500 on this computer, and I've only had it for a year.

My system specs are as followed:

CPU Speed: 2 Core 3 GHz
PSU: Corsair CX600M
Windows Version: Microsoft Windows 8 (build 9200), 64-bit
Processor: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
Graphics Card: EVGA GeForce GTX 680 2GB
RAM: 16.0 GB DDR3
Total Memory: 2TB.

Sajin
Have you changed video drivers since you bought the card? Is your CPU staying nice and cool when playing?

+1 Video drivers would be the key to start your troubleshooting as Sajin has suggested.

Have you been using geforce experience to optimize your games?

So you have all of these options unticked...
 

 
You haven't been using the optimize button for your games...

Are you running with VSYNC enabled? If so, disable it.

Gasmask

Sajin
Are you running with VSYNC enabled? If so, disable it.

V-Sync has been turned off.

Frame rates still the same?

Ok, here is what I recommend you do...
 
#1 Perform a clean installation of video drivers.

1. Uninstall Precision X/Afterburner if installed, make sure to select "no" to saving profiles when asked. Reboot the machine.
2. Download & save 332.21 driver to your desktop. (Going to start off with some older drivers first.)
3. Double click on 332.21-desktop-win8-win7-winvista-64bit-english-whql.exe located on your desktop & run the extractor.
4. Select custom advanced install, under custom installation options uncheck all options but graphics driver & physx system software, if you are using audio over HDMI please select the HD Audio driver, if you have a 3D capable monitor and would like to use 3D at some point select the 3D Vision driver also, check mark perform clean install, then click next to install the driver, reboot when asked. (Do not install geforce expereince.)
5. Re-install Precision X/Afterburner if you want, do not install both choose one or the other.

 
#2 Delete all the .cfg files for your games that contain the video settings, so they reset to default when you open the game, set settings back the way you want them.
 
Test and report back with your results.

Gasmask

Sajin
Ok, here is what I recommend you do...
 
#1 Perform a clean installation of video drivers.

1. Uninstall Precision X/Afterburner if installed, make sure to select "no" to saving profiles when asked. Reboot the machine.
2. Download & save  driver to your desktop. (Going to start off with some older drivers first.)
3. Double click on 332.21-desktop-win8-win7-winvista-64bit-english-whql.exe located on your desktop & run the extractor.
4. Select custom advanced install, under custom installation options uncheck all options but graphics driver & physx system software, if you are using audio over HDMI please select the HD Audio driver, if you have a 3D capable monitor and would like to use 3D at some point select the 3D Vision driver also, check mark perform clean install, then click next to install the driver, reboot when asked. (Do not install geforce expereince.)
5. Re-install Precision X/Afterburner if you want, do not install both choose one or the other.

 
#2 Delete all the .cfg files for your games that contain the video settings, so they reset to default when you open the game, set settings back the way you want them.
 
Test and report back with your results.

Played a game of WoT, and the frame rate was around 40 now, and it was choppy as hell. Should I install the new driver?

Yes, install 337.88 just like you installed 332.21.

Removing the 640 GPU will only decrease performance on the 680 when playing games that use PhysX and only if it was being used as the PhysX processor.

I just ran the heaven benchmark on my 2600K @ 4.2 and GTX 770 and got 1642 in Heaven at the same settings you had, I just wanted to let ya know that the 680 and 770 are suppose to be very close in performance so you are a little bit short on that score.