System temperature question-790XTA-UD4

[Bartmole]

I don't usually check because my CPU always reads fine but today I checked the Bios and it shows the System as 45C while my CPU shows 33C. SpeedFan shows the same, how is this even possible? A computer 3' away reads 33C, inside room temp is 22C, removing side makes about 4C difference, lots of fans and airflow, aftermarket heatsink. Something else must be being read but what? Thanks

[absic]

Hi there,

not exactly which temperature is being reported here. Have you tried HW Monitor: http://www.cpuid.com/softwares/hwmonitor.html to show your system temps. If you can run this and post back a screenshot it might help point you in the right direction.

A couple of things that you can check out would be the heatsinks. Are they sitting properly and not been knocked loose as there can sometimes be issues with the these.

When you changed the stock cooler on your CPU what did you replace it with?
You say you have lots of fans and airflow but have you got a positive airflow through the case, forcing the warm air out? Lots of fans, if set incorrectly can have the opposite effect.

[Bartmole]

The Heatsink is a Noctua 6 pipe with a 120 MM fan of approx 70 cfm. What catches my attention is that air exiting the case isn't much over room temp and removing the side and exposing to very cold air (10-12C) only makes about 4C difference. I'll check fan positioning now but I think airflow iis good. Thanks Edit: this is under no load at all.

[absic]

Hi there,

If I remember correctly the TMPIN0 reading on the GA-790XTA-UD4 is from a sensor located on the motherboard, near the CPU.
The possible reason for the higher temperature reading could be if your Noctua cooler is not one of those of a similar design to the stock cooler. If it is designed with the fan mounted on one side of the cooler, drawing air from the front to the back of the PC Case then maybe there is a dead spot which is not being caught as it would be with a top down design.

A quick search on the internet throws up several instances of the TMPIN0 temperature being reported within the same range as yours is doing. Although it looks worrying I don't think it will cause too much concern. If you want to try and bring the temp down then getting hold of a small fan and aiming it at the CPU area of the motherboard, might help.

[Bartmole]

I don't think it's of any great concern either, just don't like seeing it. This computer build is 6-8 months old and used for labor intensive video. I would think any problem would have shown by now. BTW, this is the heatsink with stock fan, I swapped the fan at build for an LED version and my tubes are copper. Thankyou for the help.

[absic]

well with that cooler I would of thought enough air was being blown down onto the motherboard.
Does the design allow you to rotate it's position?
Maybe turning the cooler through 90 or 180 degrees might help the situation a little.

[Bartmole]

I suppose I could turn the Heatsink but I don't really want to get into that and if taking the case side off and exposing to cold air didn't help, not sure that would either. My System temp is just wrong, right now the PSU isn't even venting at 46C and interior air being expelled is cool and not much above room temp. Guess I'll just have to live with it and sorry I even saw it.

[bytheway_r]

I'd say a faulty sensor or some extremely rare situation ( like, something warm near the sensor ). I have the same motherboard, with a Scythe Mugen II, which isn't providing any air to CPU surrounding area. My temps at idle are: system - 27-28 degrees, CPU - 21-22 degrees, NB - 30 degrees. I have good airflow, though. Still, I don't think you could have system temp being that much higher. I also don't exceed ~35 degrees system under load.

[Bartmole]

No, I've used maybe 1/2 dozen Gigabyte  boards, never seen system over 35C. I think this a very early production board, I've contacted Gigabyte, maybe there was a glitch early on. My CPU can't be 27C and system at 47C while venting fairly cool air, I doubt system is even at 30C.

[absic]

Unfortunately the sensors are not always reliable and are prone to giving up. I have had a motherboard sensor showing an obviously incorrect 165C and even had one showing absolute zero -273C. If everything else within the system is operating properly then, as bytheway_r says, it is probably just that, a faulty sensor.

[bytheway_r]

For the record, I have an old Pentium IV that's reporting 16 degrees in idle which is lower than ambient .

[jolphil]

Hi,
I also think it must be a sensor..Most motherboard sensors use "Thermistors" a highly negative TC (temperature Coefficient), thus it's a non linear temperature resistor ..Higher temp, lower resistance,Lower temp higher resistance..
Thermistors are somewhat notorious for being a bit unstable/repeatable, and also during the board solder process have been noted to change resistance due to the solder heat from the wave soldering machine..
This is also true on my board the GA-870A-UD3 board..
I do not know any Manufacturer including Gigabyte that publish where they place the thermistors.. At least that would give you a clue as what to look for..You can only imagine the difficulty it must be to get some electronics device to read accurately it's resistance/temperature
with such a device..But it is very low cost..Nuff Said
Goodluck,
jolphil

BTW: Most CPU's use a temperature sensing diode instead of a thermistor..

[Dark Mantis]

Quite right jolphil. The better way to go would be digital sensors rather than analogue but as you say it is costs and the digital answer costs more.