quick xp90 question

[calvie018]

ok, this is a newb question, but what direction does the xp-90 heatsink go in? does the overhang part go over the ram area? or the pci area? does it matter?

[fartonmyear]

i have mine overhanging the ram

[calvie018]

wow that was fast!

 

do you know if there's any particular direction that's better for cooling?

[PoppyMcShotgun]

Yes, mine overhangs on the RAM as well. It provides some really decent airflow over them!

[calvie018]

cool thx! gotta switch it around now! lol. i put it in the other way =.

[red930]

See my post below that makes this one useless...

 

You want the ends of the heatpipes to point up in a tower case. If you invert the heatsink the heatpipes will not work properly.

[ludeboy12]

You want the ends of the heatpipes to point up in a tower case. If you invert the heatsink the heatpipes will not work properly.

 

 

really.....that means in my case since the mobo is upside down that i should have mine facing the pci-x slots.....

 

hmm.....dunno how good that fits....def dont think it will fit when my 7800gtx ko arrives....

 

my temps are great though the way it is....

[red930]

The Thermalright web page has one line in their FAQ that says the heatpipes are designed to work in any orientation.

 

But! That statement is in direct conflict with the basic principle of how and why heatpipes work in the first place.

 

Heatpipes work using a process called phase change. A medium is placed inside the heatpipes during manufacture. This material will heat up and turn to vapor carrying the heat away from the source. As the material moves up and away from the source it will condense back into a liquid as it cools. Gravity helps it flow back down to the bottom to complete the cycle. This process continuously moves heat away from the source and replaces it with cooled material.

 

With that said, below is a more specific discussion of the XP-90/PX-120 setup.

 

If you orient your heatsink like the letter "U", the process will work from the bottom of the "U" to the high points at the top. This gives you the greater surface area at the bottom for the material to take-up the heat. It also places the greater quantity of material at the closest point to the heat source.

 

If you orient your heatsink like the letter "n", you end up with the greater volume of material at the ends of the heatpipes farthest away from the source.

 

The big difference is the relative size of the liquid reservoir available at the "bottom" of the setup. This is where the material will take-up heat and move it away to the "top" of the heatpipes.

 

When looking at the heatsink you will notice that the bottom of the "U" shape is where the heatpipes are closest to the heat source. The fins at the top of the heatsink where the fan mounts aren't connected directly to the base of the heatsink. This allows for a greater temperature differential between the bottom and the top of the longest sections of heatpipe and greater efficiency.

 

The inside of the heatpipe is designed to "wick" the vapor away from the heat source. This is the reason that you can use the XP-90/PX-120 setup inverted like the letter "n". In this orientation there is a reduction in the ability to move the heat away from the source.

 

I have just completed a series of tests using my XP-90 and Arctic Silver 5 in both orientations and wasn't able to detect a difference in temps outside the margin of error.

 

In conclusion, the overall efficiency of the XP-90/PX-120 setup is greater than any reduction you may encounter while using it in the inverted position.

 

With this new information I must retract my previous statement...

"You want the ends of the heatpipes to point up in a tower case. If you invert the heatsink the heatpipes will not work properly."

 

In the end I choose to keep my setup with the heatpipes in the "U" orientation for more practical reasons..

 

See here for more information...

http://www.cheresources.com/htpipes.shtml

 

ExRoadie