So i ordered one and for some reason i accidentally got the 70mm one instead of the 80mm one. (just a simple stock replacement)
I was still able to put it on fine and clipped in just like the stock one was even though it was a different size.
I figured 70mm wouldn't make much of a difference... as long as it still fits. which it does.
Stock CPU fans are just that, if a 70mm fan was adequate the system builder/manufacturer would have used one, the 80mm type was obviously deemed the most effective so I would recommend you source an 80mm fan a.s.a.p.
but it still goes black after like 15 min.
is there a problem with the new cooler?
also it came with pre applied thermal grease in the shape of a circle while the area it goes onto is a square... could this be the problem?
Also, I realized after removing my old cpu heat sink that the thermal grease seamed dried up... is it possible that was the only problem?
but if so why is the new one not working?
In addition to the possibility that the size of the CPU fan is too small there are other possibilities;
1: The CPU fan is on upside down resulting in warm air actually being drawn down towards the CPU instead of away from.
2: The fins on the heat sink being clogged with dust preventing adequate air circulation.
3: Insufficient front to rear case extraction resulting in warm air being recirculated and thus becoming hot air.
4: Untidy cabling/ribbons restricting air flow resulting in the same outcome as No 3.
5: Insufficient TIM applied, see below;
For the TIM (thermal interface material) information I suggest you read the tutorial written by Digerati
The above list is in no particular order but insufficient TIM has an immediate affect whereas dust build up or poor cooling kills your computer over time.
You have not mentioned whether you have an add on video card!
If you do this is also worthy of attention, does it have a cooling fan and if so is the fan clean and working correctly, if you have an add on card that has no fan but is cooled by a heat sink is the heat sink free of dust or even in place, they can sometimes become detached and need to be reattached using TIM.
Above is some food for thought and hopefully it will help you to resolve the issue, let us know how it goes or if we can be of assistance.