Overheating problems

Ever since I've had this computer (about half a year) I've had problems with the cpu temperature reaching its max, which in turn makes video games stutter and lag. when i first start the game it plays perfectly but after a little while of playing the games it slows down. I've replaced the cpu fan twice and it still seems to be heating up at the same rates.

so my question is, would it be a problem with just the cpu or could it be a problem with my motherboard. What i think the problem is, would be that if i use an inferior motherboard it might have negitive effects on the cpu and its heat output.

just to clarify, i have made sure to apply the heat sink\fan properly with the correct amount of thermo-paste but it still reaches 60+ within a few minuets of game play.

motherboard - Asus M2N-MX SE plus
Cpu - AMD Athlon 64 X2 5000+ (not overclocked)
Heatsink - Zerotherm BTF90
Gpu - Radeon HD 4850 (not overclocked)

I can't remember the memory type, harddrive or cd drive

Pretty much i'm willing to buy a new cpu or motherboard, or even both but i'd like to have an idea of where the problem stems and how to fix it. any help would be great

The reason I believe my cpu is overheating is, at the point when my games slow down i check the cpu temperature using "PC Probe" which shows the temperature in the 60's. also I've had the problem where i've installed the HSF incorrectly which led to even greater temperatures (so much so that i'd turn my computer ) once i figured out what the problem was i made sure to install it correctly, and apply the thermal grease properly according to the cpu specifications. Although it gets alittle stuffy in my room during the summer months, the problem still occurs during the winter months when my room is well below normal heating standards... with the airflow problem, i have a case fan and a tower side fan (i don't know what the term is) but it should be sufficient, and i believe at no point should it allow my cpu to reach those levels.

the problem isn;t if i know the temps jive with other programs or my knowledge of my maximum temps, i know that when the cpu reaches 60 or higher. my game lags. I understand that there are no given reasons why my cpu should overheat but it doesn't change the fact that it does or the point that it makes the games lag. I understand you are trying to help me with prime95 but i don't think knowing my max temp is going to do much when i know anything above 60 makes me lag, again i do appreciate the help

aftermarket

Obviously you missed the point. The purpose was to see if they program you are using was right or waaaay off.

I've never in my life heard of lagging because of cpu heat. lagging is caused by a slow internet connection.
I think you have other issues because theres no reason a stock 5000+ would run 70c. I bet if you take the side off your case the temps drop 10c.

it has been said that bushig air into a case increases pressure and as a result the heat is raised, id suggest you just use fans to suck air out, just makesure there is ample space for fresh air to get in, but getting an aftermarket cooler wouldnt hurt

Last I checked a Zerotherm BTF90 WAS aftermarket. Why bother posting if you dont even read the thread?

i thought it might be clogged fans so i took the zerotherm out and cleaned it nice, but still it doesn't cool the cpu down differently. The fan speed is fine at about 2500 rpm. and i'll have to take a look at the bios settings but i haven't changed much with my bios