FPS Problems during Gaming... HELP!

[Killer3GS]

Hey guys:
I got an ASUS G51J-3D GAMING (WTF !) Laptop about 2 years ago, and everything was going well until 2 months ago, I started to have problems with FPS. My problem is:
when I play ANY game (no matter how old or new it is) I am having an occasional/random FPS drops suddenly, Like I play 5-10 (no more) minutes normally. And then,all of a sudden, the FPS is dropped to very low (and when I say very low, I mean it. Like 1-3 FPS !!!). The low FPS issue stays like another 5-10 minutes, then everything is back to normal, and so on...
This is really annoying
I completely did a non-quick format for my entire HDD and installed a clean Windows 7 64-Bits (the same one that came with my laptop) and that didn't fix the problem.
and I'm having this exact problems with ALL my games. for example: MW2,Borderlands, Portal 1&2,Tom Clancy's H.A.W.X,UT3, and old games like Mirror's Edge and even QUAKE LIVE!!!
all those was working perfectly without having any problems before.
my specs are:
Intel Core i7 720QM
4 GB DDR3 RAM
NVIDIA GeForce GTX 260M with 1GB DDR3
Windows 7 64-bits with latest Kaspersky Internet Security 2012 (Yes, I tried to pause protection and even exit the program, and that didn't work)
and here's the web page of my laptop incase you want it : http/www.asus.com/Notebooks/Gaming_Powerhouse/G51J_3D

PS: Windows is notifying me that I should consider replacing my battery, but I am using my laptop while it's plugged in and with High Performance plan activated.
Thank you for your time. I hope someone can help me to solve this annoying problem as I can't play games on a GAMING laptop !

I did a Temperature test as some people said it might be GPU overheating, and those are the results:
Idle:
=====
RAM usage: 43%
CPU usage: 02%

Pegatron corporation G60J: Temp: 58 C (min 55 , max 63)

Core i7:
core #0 58 C (min 55 , max 62)
core #1 57 C (min 55 , max 68)
core #2 57 C (min 55 , max 61)
core #3 57 C (min 55 , max 80)

Powers: 15.34W (min 15.34W , max 55.04W)

ST932042 3AS:
Assembly 30 C (min 27 , max 31)
Air Flow 31 C (min 27 , max 31)

NVidia GeForce GTX 260M:
Voltages: 0.85 V
Temp: 67 C (min 54 , max 67)

Battery:
Voltages: 12.30 V

Playing COD MW2 online with 4 FPS:
==================================
RAM usage: 75%
CPU usage: 13%

Pegatron corporation G60J: Temp: 87 C (min 69 , max 96)

Core i7:
core #0 86 C (min 70 , max 98)
core #1 87 C (min 70 , max 94)
core #2 86 C (min 70 , max 94)
core #3 89 C (min 70 , max 97)

Powers: 15.34W (min 15.34W , max 55.04W)

ST932042 3AS:
Assembly 40 C (min 36 , max 41)
Air Flow 40 C (min 36 , max 41)

NVidia GeForce GTX 260M:
Voltages: 0.85 V
Temp: 104 C (min 77 , max 110)

Battery:
Voltages: 12.30 V

What do u think guys ??? Is it normal ??? What's the problem ???

 

[teleman56]

Have you made sure the cooling fan is operating properly? Has it been cleaned of dust, etc.?
Might be time to invest in a chiller pad for the laptop.

BTW, the baterry is used even though AC is plugged in. Best for battery life to remove the battery if you will be running extending time on AC power (extends the battery life)

 

[Killer3GS]

Thanks for the Answer and sorry for the late reply.
No, the cooling fan hasn't been cleaned ever. and it seem to work properly (it's sound).
and thanks for the Battery advice, I'll stick to it !