Altitude & Temp questions

[fr500]

Hi

I'm new here, I have a question, does altitude above mean sea level affect temperature sensors in some way, I live in a cool region (16ºc ambient outside), but always my temps are higher than what I see on forums, no matter open bench or internal, I'm always 10ºc or so above what I've notices people is running average. I'm at 2500mts AMSL

I have several systems, one is an old Alienware P1 chasis watercooled with the following hardware

- Koolance Exos-2 WC
- eVGA 750i FTW
- Intel C2D e8500 (water cooled)
- 2x8800GTX SLI (water cooled separate loop)
- 8GB DDR2 (PC2-8500 Corsair Dominator)

This PC idles at 38-40c @3.8GHz with 1.25v, pushing it down to stock frequency doesnt affect much idle temperature, maybe a degree or so, under load goes up to 58-60ºc according to coretemp coupe of degrees lower in realtemp.

Same for GPUs, when I was running on air the poor ventilated case meant I reached 103ºc when playing GRID or in the DMC4 cutscenes that ran at 120+fps which got me worried, now with watercooling i get 70ºc max, but it is still higher than the mean I've noticed on similar hardware.

Even my atom board idles at 43ºc on the bench and at 48ºc inside my APEX MI-100 case goes up to 60ºc when stress testing

Don't get me wrong, my systems are rock solid but I've always wondered if altitude may be a factor cosnidering I've tested many PCs and found similar results.

 

[BillParrish]

does altitude above mean sea level affect temperature sensors in some way

Altitude should not affect the normal thermistor temp sensors used on boards and the DTS internal die temp sensors built into the C2D CPU most certainly would not be affected.

The thermistor sensors use a physical properly of the material they are made of and work by changing their resistance to electrical current as temperatures change. In the link below you will notice that the equations for operation do not use altitude or air pressure etc. at all.

http://en.wikipedia.org/wiki/Thermistor

The temps you report are very close to mine and do not seem out of line. I run my fans fairly quiet. Only other comment I can make is that that the air up there ( approx 8000 ft ? ) has to be thinner as in less dense and a Google of "air density vs altitude" gave this http://www.engineeringtoolbox.com/air-altitude-density-volume-d_195.html along with other results.

So you might be on to something, I do not think your temp sensors are affected however the ability of the "thinner" air to remove heat from the heatsink/radiator etc. and possibility of the fans not working efficiently (not sure have to think about that one) are interesting questions. I am sure a little research will answer that as such questions would have been answered long ago in regards to piston engine aircraft engines and myriad other items designed to work at high altitudes and needing cooling.

So I am pretty sure your altitude is affecting your temps but by reducing the effectiveness of your cooling solutions. By how much is a good question.

 

[fr500]

I see yes it makes sense so to check that my readings are accurate I could use a laser thermometer I guess just to clear my doubts, and I'll be happy with my system running stable as it is now.

I didn't know how was temperature measured on processors, makes sense, I remember physics lessons and the relationship between temperature and resistance. Just never thought it was an application of that.

Maybe some one else has more insight knowledge about this

 

[sirmonkey1985]

how high up is 2500mts? lol im not a mountain person.. but the higher up you are the thinner the air is.. thus less air is being moved at the same rpm's as there would be at sea level.. so your temps will go up..