Maximum PC

What's the approximate normal idle temp for an AMD Athlon II x4 630 running at stock speeds and using a stock cooler (assuming a basic cooling setup in the case--1 120mm intake fan and a 120mm intake fan in the back of the case, nothing extensive).

Mine seems to like to idle about 38-40 degrees C. Is this normal? I've tried re-doing the thermal paste, but it seems to end up at the around the same idle temp each time. I'm using Arctic Silver 5 from Antec, by the way.

(I actually was going ot use a CoolerMaster Hyper 212+ but found out my case is about 2 inches too narrow, so I'm stuck with the OEM cooler for now).

or if anyone has any suggestions for a good copper or copper/aluminum cooler that doesn't stand up more than about 3 inches off the board, and offers good cooling (the case I'm using is a MicroATX case made by CoolerMaster).

The back fan is an intake fan?

The back should be exhaust for the best airflow.

Id say that you are in the norm with those temps.

My Phenom X4 9750 with stock heatsink and stock clock rate (2.4Ghz) was idling at 51C, and was in a room with an ambient temp of 20C.
After adding an A70 Corsair cooler and overclocking it to 2.9Ghz, I idle at exactly 40C. Honestly, id say your stock heatsink is doing a fine job.

PS: Learn from my experience, and research your aftermarket cooler in regards to its mounts to your AMD/Intel processor socket types. The A70 I mounted will only mount vertically (air flowing north and south) when with an AMD socket, and runs horizontally with Intels sockets. You CAN modify it if you look up the methods, but just be aware if you do choose to go aftermarket aircooling in the future.
Good luck man!

did I say the back fan was intake... it's an exhaust (my error in typing). I have a 120mm fan in the front that is an intake fan, and a rear 92mm fan that is an exhaust fan. I also am going to put an 80mm fan in the side panel if it gets too bad.

Generally, when people put 80mm fans in the side panels (or whatever size) do you have it pull are INTO the case or expell air OUT of the case form the side panel fan? My thought is that you want cool air coming in by the graphics card or CPU and then as it rises, it gets pushed out the back by the exhaust fan.

In my setup, all my fans pull in cold air, and the PSU and back panel fans are exhaust.

Also, try doing some cable management and get anything you can out of the way of the airflow.