A while after I got my new computer with a dual core processor, games like TF2 and L4D2, games that required moderately decent computers to run, ran extremely slowly, skipping sound, running almost at half the speed they should be. I found out that if I went into the processes tab and went to hl2.exe, or l4d2.exe and right clicked and set the affinity to CPU 0 off and CPU 1 on, the game ran fine. Just today, I started the get that skipping sound and slowness again, even though the one core was off. I'm not sure if other games require me to change cores, but I usually do it for most games on the Source engine. Games like HL2 and garrys mod run a little slower if i don't set their affinity.
•Why did I need to set the games to 1 core in the first place?
•Why did the problem rise again today?