XP-90 not cooling as well as it should, any suggestions?

[Crovax33]

So I bought an XP-90 because I wanted to make the jump into overclocking, but had little to no headroom with the stock cooler. My idle temps were extremely good with stock (sometimes as low as 27 C, and its not even that cold in my room), but the load temps were upwards of 55 (hitting 58 C every once in a while.) I asked around, and the XP-90 and a 92MM enermax fan with an adjustable RPM were what I ordered.

So I took my stock off, and put on the XP-90 with a dot of AS5 about 1/2 the size of a BB in the middle of the chip (don't worry, I cleaned off the old stuff first.) Hooked the enermax up to the mobo, then powered up and my temps were much higher than expected.

I thought maybe it was just the AS5 burn-in time, but now I'm guessing I did something wrong. I'm idling at 35, and load temps are hitting up to 55C. What gives?

Some things I thought might be it:

1. I need to plug the fan into the PSU instead of the mobo
2. I need to spread the AS5 out with a razor blade
3. I need to lap the heatsink

Hopefully you guys can point me in the right direction!

[Vihsadas]

You really should do number two. When I install a new sink, I take a very small dab of thermal grease, and then I massage it into the heatspreader and the sink base. Then I gently clean it off with a plastic bag. This will ensure that the microscopic valleys are filled with thermal grease for maximum conductivity.

[Beenthere]

In addition you may have inaccurate temps as it is impossible for the idle temp to be lower than the ambient room temp. You indicated with the stock heatsink that sometimes it was as low as 27C and the room temp was NOT that cool. That is a physical impossibility as the heatsink can't run at a temp lower than the cooling medium.

You only want a thin film of thermal compound on the heatsink. You should almost be able to see completely thru it like it's just translucent. Lapping the XP-90 base, which is pretty good as delivered, has only shown 1 degree C improvement.

Is the fan running at full speed or a lower speed? This will have the biggest impact on temps. The idle and load temps will be higher or lower based on the ambient room temp. Typically with an XP-90 and good airflow thru the case and the proper size fan and fan speed the increase under full load is 15c above ambient.

This test is in German but if you look at the temperature Delta for the XP-90 under full load its = 15C. Your results should be quite similar if you have good case airflow and the proper 90/92mm fan and fan speed.

http://www.planet3dnow.de/artikel/ha...yper48/4.shtml

[mcoleg]

according to a freind of mine who just got one, it needs some hardcore lapping... check here:

http://www.ocforums.com/showthread.p...&page=10&pp=30

in the middle of the page there some pix.

[Beenthere]

Thermalright's heatsink bases are very flat. Hard to say what the deal is in the other thread. You can check your heatsink with a straight edge and a back light. Place a quality straight edge like a 6" machinist scale on the clean heatsink base and with a light behind the scale you can see any high or low spots. You can place the scale diagonally corner to corner and in the middle in both directions. Based on any number of XP-90 and XP-120 reviews these heatsinks have a flat surface and generally quite smooth. They are not lapped and for some folks they view this as criminal... In reality the difference in temp on the XP-90/120 before and after lapping is 1 degree C unless of course you have some really exceptionally warped heatsink, which would be very rare. FWIW I have a new XP-90 here and it is quite smooth and flat as was the case in this review and others.

http://www.silentpcreview.com/article194-page2.html

[Ray Von UK]

sounds like its not fitted properly,
Give it a check and your case temp can be less than that outside the case quite easily if you have fans in and around the case.
TBH also i have hed like 8 heatsinks and never felt the need to lap a single one,
Remember lapping can also ruin the surface as well as improove it

[Crovax33]

Unfortunately, my case temp sensor is broken (it is constantly reading out 12 C).

So I have two broken sensors: a video card one and a case one. Joy.

[Crovax33]

So here's what I did.

I took the heatsink off, cleaned it and the chip off with alcohol (99%). Then I took some as5 and rubbed it into the the heatsink with part of a plastic bag. Then I took another part and cleaned it off (you could still see a small amount wedged in the grooves.) I then took a razorblade and spread AS5 over the whole chip. A very VERY thin layer, but it's covering the whole thing.

Temps are not too much better right now. 35C idle. I'm hoping that with break-in it will go down.

[scrandman]

How's the airflow in and out of your case? If the airflow is poor, your fan will just be pushing hot air onto the HS.

[Beenthere]

Poor airflow thru the case is usually the problem when everything else is correct. Break-in or curing of the AS will only improve the temp a degree or two. That isn't the solution to the problem. You can't cool the CPU with hot air. You must have good airflow thru the case to get the hot air out and cooler room air in. The higher the room air temp the higher the CPU/case operating temps even with good airflow.

Ray Von UK you stated:

"Give it a check and your case temp can be less than that outside the case quite easily if you have fans in and around the case."

NO, this is physically IMPOSSSIBLE. The temp inside the case can NOT be cooler than the ambient room air unless you are running a vapor chill system. You can have a thousand fans blowing in and around the case but the lowest the case or CPU temp can ever be is whatever the cooling medium temp is and that's the ambient room temp in an air-cooled system.

[Rickikaye69]

wind chill mate

[Crovax33]

I have 4 case fans (two intake and two exhaust) so I can't see that being too big of a problem. The temp in my room is about 75 degrees F.

EDIT: I tried taking the side off my case and putting a room fan blowing directly on the heatsink, and it hasn't helped my temps at all. They are the same as without. So the problem is NOT bad airflow.

[_dangtx_]

bad sensors

[Beenthere]

Yup, if you removed the side panel and the temps didn't change I'd suspect the temp readouts are incorrect.

By the way "Ricki MATE" there is no such thing as "Wind chill" for inanimate objects. The only means to get a lower case temp than air temp is if the room relative humidity is 100% and then you have water VAPOR cooling, not air cooling.

[Rickikaye69]

BS you go stand in the cold and see how cold you get, then go stand in the cold with 30mph wind, what's colder? the wind obviously.