AMD Stock Heatsink has Fan attached backwards?

[cbrunny]

Looking at the stock heatsink on my new FX-8350, the fan is on the top blowing down into the heatsink. This just seems wrong to me. Shouldn't it be blowing the hot air out, not down into the cpu?

I noticed the same thing on my old 1055T, and I flipped it. This dropped temps by ~15 degrees C. But if there is a reason not to, then I wont.

 

[cbrunny]

Flipped the fan... now running 10 degrees cooler while prime testing. Noisier under load, but worth it for the 10 degrees imo.

 

[crashtech]

What?

 

[aigomorla]

Ok im lost in how flipping ur fan that way gave u better cpu temps.

First off what program are u using for temps.
Second im guessing its your motherboard diode which is a bad way to get cpu temps.
Third u push fresh air from the top though the sink. Not warm air from the board though the sink.

This is why ur diode shows a temp drop. Your cooling the wrong diode.
Or ur sink has no air gap to get fresh air the proper way.

 

[sandorski]

It has always been this way, for AMD, Intel, VIA, etc. Only a few OEM HS/Fan setups have done it different.

 

[cbrunny]

Mobo is Asus Sabertooth 990FX r2.0, and the temps are coming from the "thermal radar".

Not sure what you mean by motherboard diode being a bad way to get cpu temps.

 

[crashtech]

I've never seen an integrated HSF assy that sucks air upward over the fins, and I've seen a few in the last couple decades.

The only exception is when there are two fans in tandem, one pushes air into the fins, and another extracts it.

The part about your assertion that the CPU runs cooler with the fan reversed is a puzzler, hence the suggestion that the temp you are reading mistakenly comes from another sensor besides the CPU.

 

[cbrunny]

I will see about taking some photos when I have a chance.

 

[aigomorla]

Mobo is Asus Sabertooth 990FX r2.0, and the temps are coming from the "thermal radar".

Not sure what you mean by motherboard diode being a bad way to get cpu temps.

That is a motherboard probe which sits near your cpu socket.

NOT a good way to get cpu temps.

You need to run a program like coretemp, realtemp.


Anyhow the cooler the air the better.
Where do u think ur gonna get coolest air though your sink?
90% of the time its not going be getting recycled air from your board where your mosfets will be dumping heat from.

 

[cbrunny]

Respectfully, why would a third party freeware deliver a more accurate temp than first party mobo sensors/software?

 

[crashtech]

Without knowing anything about this "Thermal Radar," the kind of result you describe deserves some verification, a second opinion, if you will. You should be able to see eight different thermal readouts for your CPU, are they all showing the same temperature drop? Would it hurt to bring CoreTemp into play just for fun?

 

[MrK6]

The fan is supposed to blow cooler air directly onto the heatsink and then your chassis fans should whisk away the warmed air that is pushed out the sides. If your motherboard temps dropped from reversing your CPU heatsink fan, it sounds like you could use more airflow in your case. I would also check the actual temp of your CPU using RealTemp or CoreTemp. You use these programs because they are designed to read from the diodes in the CPU die.

 

[cbrunny]

Core temp causes my computer to blue screen. Not sure why - this is new behavior.

Even so, I still have no idea why software that came with my motherboard would tell me temps specifically for my CPU that are not actually for my CPU. The board is a higher end board. It simply makes zero sense.

My airflow is fine. I have four intake, four exhaust fans plus the GPU and CPU fans.

I will spend some time getting screenshots in order. A second opinion would be helpful.

 

[blastingcap]

The fan is supposed to blow cooler air directly onto the heatsink and then your chassis fans should whisk away the warmed air that is pushed out the sides. If your motherboard temps dropped from reversing your CPU heatsink fan, it sounds like you could use more airflow in your case. I would also check the actual temp of your CPU using RealTemp or CoreTemp. You use these programs because they are designed to read from the diodes in the CPU die.

this

 

[cbrunny]

Real Temp does not support FX-8350.

 

[cbrunny]

Screenshots:

Front-facing (The way AMD makes it)
Idle:


Uploaded with ImageShack.us

Load:


Uploaded with ImageShack.us

Fan Flipped (not the way AMD makes it)
Idle:


Uploaded with ImageShack.us

Load:


Uploaded with ImageShack.us

 

[cbrunny]

Updated to newest version of Core Temp, ran some basic diagnostics and now it seems to work. Prime95 was run for 10 minutes to get the load temps.

Weird stuff. The Thermal Radar definitely isn't correct - assuming of course that Core Temp is correct. Good to know.

So, load temps are cooler if the fan is flipped, but the fan RPMs are way higher (2000+ RPMs), and cpu fan is significantly louder. Not sure why the fan would be rotating faster if it was flipped though. I didn't manually adjust any fan speeds here - the bios took control of all of them. Could be an air pressure thing I suppose. Not sure.

 

[jaqie]

there are a few that run exhaust instead of impagnation, the first that comes to mind is the ALPHA PAL8045, one of the first ever to use the socket A through-motherboard mounting holes. It did indeed keep the cpu cooler, it was an early and very massive for the time pin-fin copper core aluminum fin heatsink. For most heatsinks impagnation works far better than exhaust, but there are a few that exhaust works better on.

http://www.tweaktown.com/reviews/114/alpha_pal8045_heatsink_review/index.html

The reason the fan sounds louder and is running faster is it is scooping the air right off the heatsink fins and is almost touching them. With a setup like that you need to space the fan away from the heatsink by a half an inch, look at the PAL8045 it has a sleeve that does that from factory.

 

[crashtech]

jaqie, the linked article shows the fan mounted in the other direction.

 

[jaqie]

and the original instructions from the manufacturer say don't do that.

That isn't even the original fan.

 

[crashtech]

So the Tweaktown got class-leading results with the fan mounted backwards... interesting!

 

[jaqie]

Especially since they used one of those screaming 7k rpm fans to do it, and hardocp did a huge investigation into this and found that almost the same results could be gotten with the included fan mounted how the OEM specifies!

I am on 3g cellphone net from cricket right now while I wait for dsl to be installed. I didn't even look at tt's site, at least I linked it for the benefit of others. This net is horrible slow.

 

[cbrunny]

So the Tweaktown got class-leading results with the fan mounted backwards... interesting!

Affirms that I'm not crazy!

 

[crashtech]

Well, backwards in their case actually means forwards, and opposite of your preferred fan orientation, so perhaps the jury is still out on the mental health issue...

Honestly, as long as there is plenty of air movement, there isn't going to be any harm done. But I'm still dubious of the results obtained here, if your results are genuinely the case, why haven't more enthusiasts picked up on the massive cooling gains available simply by flipping a fan over?

 

[SpeedTester]

Affirms that I'm not crazy!

I can assure you by mounting your fan in pull mode you are not improving anything.
I still have my old 8045 around somewhere and did run pulling air off the heatsink but also had a duct directly over it venting outside the case door. I tried both ways and barely noticed any difference.