i just want to know if this is ok to cool my system
First of all, i am no overclocker and i do not have the cash so i just stick to the stock CPU cooler. my cpu is an intel pentium d 820.
Second, please do not say that i should upgrade this and that because i am really short on cash..
I have a generic case with 2 slots for 80mm fans, one in the rear and one on the side. I have an intake fan on the side because if i make it exhaust then it would blow hot air to my monitor (CRT monitor..i know its old).
My question is that can i put an exhaust fan in the rear? is it ok to put a fan in the rear because it is so close to the cpu cooler?
It is the correct flow... You want at least one fan as intake and one fan as an exhaust. It is normally recommended to have the back of the case as an exhaust. Your fan isn't too close & won't cause an issue.
In my Antec 1200, I have the front fans as intake and the top and back as exhaust, which is the "greater" version of your setup.
Putting an exhaust fan in the rear would be a good idea if your case supports it. Having a rear exhaust fan close to the CPU cooler isn't likely to be an issue. What CPU and stock cooler are you using. If you have a cooler that had a fan on the front blowing air through a heatsink then out towards the back of the case then a rear exhaust fan would help to create a wind tunnel effect where the CPU fan blows air towards the back of the case and it is then blown out the back.
I have to say though, do you even need extra cooling? I would use a CPU temperature checking utility to see if you even need to install and extra fan.