When you're gaming and for prolonged periods, you tax the system. After sometime, it will start to falter, and/or the weak link becomes apparent. Notice, you gave no mention of your PSU. This many times is the weak link and under heat stress becomes weaker. The outputs fall or it drops some voltage and/or it reaches a critical level and shutdown to save itself. While, this is happening, it becomes what I term a "flaky system". Replacing the PSU with a higher wattage one and of a name brand should help. Even, if a system is well cooled, hot spots are within the system, the video card and/or immediate area is prone to heat duress and/or lessen airflow. It boils down that over time, some weak link is noticed. That's why it pays attention to details to include the PSU and cooling. This doesn't exclude the network, working hard to keep things going as well, so that too can cause a glitch which falters the system. When gaming, you are in "high demand mode" and that basically where the system is going to sooner or later produce a problem. I exclude any s/w glitches if any exist, but it's possible, what works well for one game may not for others and/or to get to more demands on your system to maintain a good level of play.
Long story short - I'm playing a game, Lord of the Rings Online or Red Alert 3. After some time, from ten minutes to three hours, the PC rebels, monitor goes black, with Digital/Analog window twinkling in the corner and, moments later, whole PC seizing it's work (hearable, as game sound stops working a while after the monitor). Only the Start button helps then, neither Alf+f4, Alt+Cntrl+Del nor Reset helps (if I use Reset button, comp crashes right after I enter the game).
My configuration is:
Intel Pentium Dual CPU
E 2160 1.80GHz
1.84 GHZ 2GB RAM
Radeon X1950 PRO
My question is, what may be the problem and what can I do with it? Lately I've had problems with power - computer sometime refused to start to work - but I've called a technician, he changed one part and repaired the PC. Tis' rather not the heat, I've examined PC unit from the outside and couldn't feel any bigger heat.