Low FPS in games after clean install Windows 7 x64

So 2 weeks ago i did a clean install of Windows 7 x64, downloaded all the lastest drivers and all my usual programs.

But I have ran into the issue that in all my games after about 5 - 10 mins my FPS drops to the point in which I cant even play. I've already tested this on several games, all of which before the clean install ran perfectly.

Yes I have made sure there arent any processes running in the background, and I have tried using such tools as GameBooster with out any successful results.

The entire hardware of the laptop is brand new, due to the fact that its been operating w/ new hardware since last Friday.

Specs:

System Manufacturer Dell Inc.
Model Studio 1558
Total amount of system memory 4.00 GB RAM
System type 64-bit operating system
Processor Intel i5 CPU M520 @2.40GHz 2.40GHz
Number of processor cores 2

Storage Total size of hard disk(s) 466 GB
Disk partition (C 30 GB Free (65 GB Total)
Disk partition (D 176 GB Free (200 GB Total)
Disk partition (E 200 GB Free (200 GB Total)
Media drive (F CD/DVD

Graphics Display adapter type ATI Mobility Radeon HD 5400 Series
Total available graphics memory 2746 MB
Dedicated graphics memory 1024 MB
Dedicated system memory 0 MB
Shared system memory 1722 MB
Display adapter driver version 8.741.0.0
Primary monitor resolution 1920x1080 DirectX version
DirectX 10

Network Network Adapter Realtek PCIe GBE Family Controller
Network Adapter Dell Wireless 1520 Wireless-N WLAN Mini-Card

It sounds like it could possibly be due to overheating. Some laptops will reduce performance if they begin to overheat and this is most likely to happen while playing games. Do the fans all come on full? Does it feel like it is getting hot?

You may not realise this with the testing tools as they will only take a short time to run and it won't have time to overheat.

NO its not over heating since I monitor the temp, fans are working fine. I've been gaming on this laptop for exactly one year with out any issues, until the clean format. I don't believe its hardware since Feb and March i got the mobo and RAM replaced 2, and the second time I actually got a better card from Dell as a replacement, and this was last Friday, so I don't think its faulty hardware.

Try reinstalling the drivers for that card.
Happened on my desktop as well. Reinstalled graphics
card drivers rebooted and all was good.

I've reinstalled them quite a few times already with no results. I also tried previous drivers to see if those would work as well.

Kalid0r said:

It sounds like it could possibly be due to overheating. Some laptops will reduce performance if they begin to overheat and this is most likely to happen while playing games. Do the fans all come on full? Does it feel like it is getting hot?

You may not realise this with the testing tools as they will only take a short time to run and it won't have time to overheat.

Any reccomendations on monitoring software, speedfan makes my laptop freeze for some reason.

I also have a very similar issue.. installed windows 7 SP1 64 bit last week (clean install) and FPS seems to have dropped by approx. 50 frames on black ops

I seem to be have somewhat same situation, did a reinstall of the OS for C:/ folder and now my FPS's have dropped from about 110-120 to ~80. (More here: Lower FPS)

Wonder what's the reason for me...