FPS drops in ETQW with M570TU/9800M GTX notebook

I have a XXODD notebook (Dutch company) that sells CLEVO-based notebooks like the M570TU notebook.

I have a X9100 CPU, 2 x 2GB DDR3 RAM and the Geforce 9800M GTX (1GB)graphics card, HD is a 300GB 7200RPM (16MB cache).

In the game Enemy Territory Quake Wars (ETQW) I get stable FPS but every few seconds my FPS drops to below 30 FPS making the game unplayable.

I have monitored the clock settings and temperature of my graphics card whilst playing the game and there is nothing special going on. I even have this problem when I play this game with the lowest possible setting at a resolution of 640x480.

My other notebook is a M570U with a 7900 GTX graphics card (512MB) and this one can run the game without any problems.

Both notebooks have the same Intel WiFi 4946AGN adapter and they are on the same network so it should not be a network problem. I use the same drivers for the WiFi adapter as well.

I have tried a couple of different Intel Chipset drivers and I have tried many different Forceware drivers from 175.xx to even the latest 180.70 drivers. Hell, I even tried Windows XP x86 & x64, I have tried Windows Vista x86 & x64 and I even tried Windows Server 2008.

I play ETQW a lot and I bought a 3000€ notebook mostly for professional reasons but partly to have a better experience in ETQW. Now I have a fast machine but I can't play ETQW.

Does anybody out there also play ETQW on his M570TU/9800M GTX machine and experiences the same? Let's say that something might be wrong with my hardware and it is still under warranty then I need a way to figure out what is going on for the support of the manufacturer. What can I do?

I also have the Intel Turbo Memory option (2G), could this be somehow the culprit?

Also when I was running Windows Server 2008 with Hyper-V services installed then I would constantly have a FPS of below 30 in ETQW, even at 640x480 with the lowest possible settings.