Need help optimizing CPU air flow

[owlowlowl]

Hi all,

I recently put together a new machine. I found that the stock CPU cooler was much too loud for my taste, so I upgraded to a Xigmatek Dark Knight (w/ Arctic Silver 5). To my surprise, my load temps didn't decrease at all from the stock cooler. I'm wondering if anyone can lend their opinion on my setup.

CPU: AMD Phenom II X4 955 BE
Case: Antec 300
Load temps hover around 58-59 C.

Here's a picture:

(Cable management is temporary and unplanned. I will probably swap out the case fans for something quieter and I still need to install an optical drive.)


Note that the motherboard isn't quite full sized, even though it's ATX compliant. As a result, the CPU cooler covers two of the RAM slots. I was concerned that the back of the CPU fan would be so shoved against the GPU that it would impede airflow, so I mounted it near the case exhaust fan in a pull configuration. (Both case fans are set to exhaust.) I've discovered quite a bit of vitriol regarding Push vs Pull configurations, but the difference didn't seem too great.

I've read that the maximum safe temperature for my chip is 62 C. Core Temp hasn't reported anything at that yet. Even though the load temps are the same as the stock cooler, the Dark Knight is substantially quieter, which is all I really wanted. Still, I expected at least a minor drop, and lower temperatures means the fan doesn't have to work as hard.

Is it worth my hassle to remount the cooler in the other orientation? Do you think the closeless of the videocard will impede air flow? Installing it the first time was a chore in that cramped configuration, and while I'd prefer not to do it again, I'd also rather get it done with if it will help.

 

[ehume]

I suspect your pull fan and your top exhaust fan are interacting adversely.

Try this: outside your case, put two fans so that one blows into the other. First try it with the downwind fan unpowered. Then power up both fans.

Bring the upwind fan closer to the downwind fan. As the upwind fan approaches, the output of the downwind fan will decrease.

So: switch to a push configuration. Output up is fine, since the heatpipes will be horizontal.

 

[MadScientist]

If you can, try mounting the the heat sink vertically (turn it 90 degrees clockwise) and mount the heat sink fan in a push configuration so it blows air through the heat sink towards the back of the case.

 

[superccs]

^agrees with previousl comments. You need to setup some airflow paths in your case so you can get fresh air to your components and then have them exhaust it out of the case asap.

Your rear case fan is pulling air out the back, your top fan is pulling air out the top, if you can orient your CPU HSF so that it lines up with one of those airflow paths you will see your temps drop.

Right now you have no fresh airflow, and exhaust air going pretty much no where. With so much rear exhaust airflow, make sure you turn up your front intake fan so you can maintain positive pressure and ensure that fresh air comes from up from and not from your video card or something.

 

[superccs]

^agrees with previous comments. You need to setup some airflow paths in your case so you can get fresh air to your components and then have them exhaust it out of the case asap.

Your rear case fan is pulling air out the back, your top fan is pulling air out the top, if you can orient your CPU HSF so that it lines up with one of those airflow paths you will see your temps drop.

Right now you have no fresh airflow, and exhaust air going pretty much no where. With so much rear exhaust airflow, make sure you turn up your front intake fan so you can maintain positive pressure and ensure that fresh air comes from up from and not from your video card or something.

 

[Soulkeeper]

Having the fan on the top of the heatsink is bad.
If you can't turn the heatsink 90 degrees clockwise atleast put the fan on the bottom blowing air up. Then, like suggested, ensure that you have plenty of intake from the front.

 

[owlowlowl]

Thanks for the input. I was unable to mount it 90 degrees, but I reoriented it so that the fan blows into the heatsink from the bottom.

To my surprise, my load temps are now 1-2 C higher than they were before . I did change my application of thermal paste according to the findings here (used a little less than they show in the picture).

When I put my hand behind the heatsink, I feel almost no airflow. There's actually more flow from the turbulence behind the fan. Mostly it seems to just blow out the sides. I think this is because of the convex shape of the heatsink, but I'm not sure. I'm holding out hope that the temperature increase is due to the break-in period of AS5 (up to 300 hours). If not, I will add a front intake fan (I don't like how the case came with two exhaust but no intake).

 

[mv2devnull]

Thanks for the input. I was unable to mount it 90 degrees ...

Yes, it seems that DK is limited to vertical flow orientation with AMD socket, (while LGA775 socket might allow both vertical and horizontal.

How about moving the top exhaust fan to front intake slot? That would add pressure into the case (more air for the CPU fan to push into the cooler). Then again, the exhaust flow would reduce a bit.


The heatup could still be a paste gone wrong. Was there a break-in with the pull configuration?

 

[RavenSEAL]

Heatsink might not be properly placed! that's all i can think of.

 

[owlowlowl]

I'm hesitant to remount it again. Last time I managed to put some pretty deep gouges in the top of the chip. It's mostly cosmetic, but some of the metal is now pushed up and probably prevents the heatsink from resting flat. If I do it again I'll have to file that down. Come to think of it, that's probably been the problem all along.