CASE FAN

How can anyone possibly answer your question without knowing exactly what PC model you're talking about?

Is that 140ºF or 140ºC? And how do you know that's too hot?

One solution is to use Slot fans that blow out the back to pull the hot air out.

Cranky Field Mice's  removal is something else altogether.

http://www.amazon.com/StarTech-com-Expansion-Exhaust-Connector-FANCASE/dp/B0000510SS

HI,RoHe,My understanding when it comes PC temperatures is there is a standard limit as to how high they should go so you do not harm your PC.

Also i am not so stupid not to know the difference between 140 F AND 140 C,

140 DEGREES CELSIUS is 284 degrees Fahrenheit that is why i changed my Speecy from C TO F. 

140*F, 60*C, is not too hot for CPUs running  at idle, at normal ambient temperatures. Most computers will begin to throttle back in the 90s, and shut down a little warmer.

We still need to know the model.

HI,I have been trying to find out what the CFM'S are for the CPU does anybody know what it is as i want put another fan in the back to pull more thru PC,so far all i have found out is the CPU fan pushes air across the CPU and in the heat we are having my PC temperatures are a little high in the neighborhood 140 degrees and up the GPU  is running hot too,thanks

VIDEONTTT6

Has the processor's heatsink's cooling fins, fan and front panel air intakes, been cleaned of any dust build up recently?

To carry this out, you probably will to need the remove both the fan, heatsink and shroud from the chassis, see page 44 here:

 ftp.dell.com/.../dimension-e521_service%20manual_en-us.pdf

Note: The e521 is a BTX system, not ATX, the heatsink and fan are Dell proprietary parts. 

Bev.

Edited for content.

The temperatures have come down in relationship to outside temperatures coming down,but i still think it would not be a bad idea to add a fan to back of case as i did not know the front fan pulls air in across heat sink so a fan at the back would help exhaust heat out of the case.

CFM is meaningless for a fan not attached to anything. It will vary with the area of the vent holes where the fan is attached and the area  of the remaining vent holes/slots and the amount of stuff inside that will reduce air flow rate. If the fan doesn't give enough cooling, chose a larger one (based on specs amperage or wattage. A variable speed fan or an add on speed control will cost more.

Well i still have not gotten a answer from numerous form sites one of them suggested going to DELL but they do not understand DELL itself  is of no help whats so ever.

The openings in the back of case measure 3"x3" or about 76mm now all i need to find out how CFM'S i need to

make this work the fan in front of CPU pulls air in and i saw somewhere there was a way to change the speed of the fan but right i do not know where that setting is at and one of the settings said quite fan and several more

to change the fan speed.