Before I installed my SSD and reinstalled windows, I used to get over 100fps on most Battlefield 3 64player multiplayer maps. Now it drops to 45~25. Nothing else has been changed, and every driver is up to date and in the correct slot on my motherboard. Tried multiple nvidia drivers etc.
Nothing is and has ever been overclocked.
A new SSD will load maps faster, not slow down the game... something could be downclocking your game, a driver issue, or something is creating more lag as you play. Have you optimized your SSD settings already?
Are you comparing the same maps from before and now? From every account, most 64 man multiplayer maps are going to have FPS drops and there isn't much you can do about it, while single player will allow for much higher FPS.
It is highly unlikely you never saw dips below 60 FPS prior to the SSD on 64 man maps. You may have just not paid attention prior, and now you are highly focused on anything new and have been looking at your FPS.
Nope, I never dropped below 60 fps. I upgraded my system about a month before buying this SSD and I've been very focused on my fps. It's dropping below 45 fps on maps like caspian, gulf etc and it's noticeable to the eye even not looking at the frames.
Try running benchmarks and other games. Perhaps the difference is due to settings. While I find it unlikely you ever played maps like Caspian at 100+ FPS at all times, testing benchmarks can show if your system is running properly or not with something you can compare. Multiplayer is rarely ever benchmarked due to the randomness in its nature.
I ran the Heaven benchmark on a single 680 that is clocked at 1084 out of the box using the same settings as the last benchmark you posted. It appears your score is very similar to mine, which is good for a 670, depending on your clocks. By that benchmark, the 670 is performing normal.