You claim they are up to date but we can't use Windows to determine that. Nothing has changed about installing Windows. I'm going to stop here since I want to read how you determined the drivers were current.
My computer's Speccy: http://pastebin.com/pTwN7uPE
Recently, my original hdd died all of a sudden (started beeping when its powered and isn't readable) so I got a new one which is compatible with my laptop. My previous hdd was a 5400rpm and I replaced it with a Seagate ST9500423AS 7200rpm hdd. My laptop (Dell XPS M1530) is over 4 yrs old, so it could be a lot of things. My battery doesn't charge and all that good fun.
I had that 7200 lying around, never-been-touched-still-in-static-bag, and so I swapped it with the other one when it died.
After installing a clean Win7Pro, I installed all drivers (cpu, gpu,...) and they are up to date. I did not flash the BIOS b/c it still shows that it is at version A12.
Now, even with this old laptop and the slower, older hdd, I could play FIFA 13, Arkham City, and a lot of other games on lower graphics without lag. I know the BIOS throttles the cpu when it does not recognize the battery, but I could still run the games with no trouble.
Now, I cannot, things get very choppy after playing for a few minutes. I attempted forcing the cpu not to be throttled with ThrottleStop but it would just force shutdown after a little.
According to the Windows Experience Index, my rating is now up to 5.4 from 4.8 because of the upgrade from 5400 to 7200, so why is my gaming experience worse?
Are there any tests I can run to find out what the issue is? Might something else have shorted out when my hdd died? Am I just plain screwed cuz my laptop is ancient?