i have an AMD Athlon 64 x2 Dual Core Processor 6000+
at the moment i have 257 pc games over one gigabyte big, 50% percent of them are 2+ years old, and when my pc has been on for more than two hours, games like cs 1.6, gta san andreas, and c&c series (except tiberium wars) goes overspeed, like 3x to 10x faster! in gta things goes uneven 2x times faster only to go 7x faster the next so the slowitdown cheat does not work.

now it aint that a big problem, all the games goes normal speed with newly restarted pc, but gta san andreas doesn't, so this is the game id like get working. All the other would be appreciated too. As restarting my pc every time i want to play old games is a bit tiresome. this problem does not occur on newer games like crysis, source and call of duty 4.

i have tried a program called cpu killer, but it didnt work, just started lagging :P

With such new games (yes, new), the problem is most likely caused by CPU frequency scaling. The game detects your CPU speed at startup, but it doesn't know that the CPU wil up the frequency when it is used more.

Try disabling CPU speed scaling before you run these games. Game patches may be available too.