Hello lads and ladies!
 
I'm a first time builder, who yesterday completed his first system.
Unfortunetly, it appears to be running a bit hot.
 
The spec's are as follows:
Motherboard: Asus P5K SE/EPU
PSU: Corsair VX550
RAM: 2GB
CPU: Intel Core 2 Duo E8400
CPU-Fan: NorthQ NQ-3312BLA (120 mm)
Graphic Card: Inno3d GeForce 8800 GT OC
Chassis: Coolermaster Mystique 631 (rear and front fan, each 120 mm)
 
As I'm writing this and only running Winamp in the background, the CPU is at 111 Fahrenheit and the motherboard is at 104.
The CPU-fan is running at 2070 rpm's (making quite a bit of noise) and the chassis fans are each running at about 1100 to 1200 rpm's.
 
Can somebody tell me what I've done wrong?
 
Which is more likely?
The motherboard is heating the CPU or
the CPU is heating the motherboard?

Where are you reading you temps from and what program / screen ?
It could just be that that cooler happens to suck.

Redo the heatsink, put on the thermal compound you either have or need to buy, in a THIN layer and not a thick one. See if that helps.

This is a 120 mm fan...
The max rpm is 2200.

uh...those temperatures really aren't horrid, 111F = 43C. They are idling a little high for my liking but in no danger of damaging the cpu / mobo. As long as you can keep the cpu bellow 70C (158F) it should be ok.
 
That being said here are some ways to possibly lower your temps.
 
1. re-seat the heatsink (if you do this make sure to remove all the old thermal grease and apply new thermal grease. call me a fanboy but i would recommend Arctic Silver 5)
2. Make sure all the case fans are positioned in such a way that there is a good airflow through the case and no "dead spots". (This includes orginazing all the wires so they don't go every which way)
3. MAKE SURE the heatsink is pointing towards and exhaust fan, not an intake fan!
 
Thats what comes to mind right off hand, im sure there are more things that could be done but this should give you a good start

There's nothing wrong with the  temperatures you've posted except for the standard you're using. All temperatures you see on the Internet use Centigrade, not Farenheit.
 
111F = 43.9C
104F = 40C
 
When posting temperatures, in order to compare apples to apples, be specific as to ambient temperature, and state what temperature monitoring utility your using to read temperatures. Real Temp 2.6 is the most accurate. Also, be sure that your case covers are removed, all fans are at 100% RPM, and Idle is really Idle. For Load tesing use Prime95 Small FFT's.

 
yah, I saw the 120mm and edited....

 
Dude, are you sure?
 
From what I can tell Intel CPU temp should not be much above 35 centigrade, when idle.

You posted as I was editing. Take another look.

true, with a good heatsink 35 is a good idle, however with a not so good heatsink 44 could be considered a normal idle which shouldn't cause any damage to the system.  
 
I would check and post the load temperatures cause if those got too high they could damage the system (however i dont see that happening).
 
Also what are you using to check temps with, cause it might not be calibrated correctly or other such errors?
 
Also the cooler come with a layer of thermal grease already applied or did you apply an aftermarket thermal grease to it?

 
I applied thermal grease to the cooler. The thermal grease came with the cooler.

mid 40s arent that uncomon for idle, especially with speedstep off.
 
What program are you using? Use Realtemp if your not already.

how much thermal grease did you use? Use of too much thermal grease will increase temperatures as well
 
as for ^ roadrunner raises a good point. Try turning speedstep on in the bios (if it isn't already) and watch the temperatures drop!

 
I've been using PC Probe II.
 
I'll try Realtemp tomorrow

PC  Probe shows your CPU temperature, which is different from Core temperatures. This is explained in detail in my Core 2 Quad and Duo Temperature Guide. There's a link below in my signature.
 
Don't use Core Temp because it shows 10c too high on 45 nanometer processors. Only Real Temp is accurate straight out of the box. Also, 45 nanometer processors are known to have faulty DTS sensors which "stick" and won't allow the true Idle temperatures to be displayed.
 
There's a "Test Sensor" button in Real Temp that you can use to check the response of your Core temperature sensors.