I have a sony vaio laptop with intel i5-2410M 2.3 ghz, nvidia geforce gt 540m, 8 gb of ram (4x2, ddr3).
The problem started couple of months ago. I am trying to play games with good graphics, which I have been able to play with no problems at all. The game runs smoothly for 5 seconds, and then runs at very low frame rates for 2-3 seconds. It has become completely unplayable. I've tried switching to lower graphical settings, and even tried to play the game in a window (not fullscreen) and with lower resolution (the screen is hd).
Also, this doesn't happen at the first couple of minutes of playing, which led me to think that it might be a heating problem. If so, how can I be sure, and what can I do to fix it?
Another thing that comes to my mind is the ram. I have added the second 4gb later: it wasn't in the original config. Is it possible that it's causing the problem. Again, how can I confirm?
The gpu heats to 65°C while just surfing on the net. It reaches 87°C while gaming.
run memtest as soon as you can. it'll let you know if your ram is faulty as you mentioned that you installed one stick later on. it might me an issue that the ram modules are not cooperating with each other.