Strange as hell GPU temp problem

[CryptoCluster]

I have few 4 x 7970 rigs. All of them are hashing 720-750khs (litecoin currently). But on one of the rigs 3rd GPU runs a lot hotter than on others. 1, 2 and 4 GPU temps are 65-75 but 3rd GPU is 95-105!
I initially thought it is faulty GPU, but if you swap any card in that 3rd slot is starts running hot as hell.
I have tried running it using riser as well as plugged directly into motherbord pcie.

What might be the reason?

[kuusj98]

You may want to have a look at your VRM temps, you would not be the first one to blow one out...
May be that power is not distributed right, power always takes the shortest way...

[CryptoCluster]

Card on problematic pcie is now underclocked and undervolted to maintain sub-70 temps. Sadly i cannot see the VRM temps in GPU-Z or in any other monitoring software (GPUs are Gigabyta GV-R797OC-3GD voltage locked).

Is it possible that some strange mobo hardware error interferes with VRM on GPUs overvolting it somehow?

[kuusj98]

Card on problematic pcie is now underclocked and undervolted to maintain sub-70 temps. Sadly i cannot see the VRM temps in GPU-Z or in any other monitoring software (GPUs are Gigabyta GV-R797OC-3GD voltage locked).

Is it possible that some strange mobo hardware error interferes with VRM on GPUs overvolting it somehow?

Hmm, I dont think so, the clocks are handled by the gpu itself, so are the volts...

I suggest changing the PCI-e cables to that card, maybe the cable is faulty.
Does seem strange anyway...

[crazyates]

Does your 3rd slot have bad airflow?

[CryptoCluster]

Does your 3rd slot have bad airflow?

Same as other slots. Today I have tried different PSU, nothing changed.

[rascal777]

I notice that in Cgminer that the Temps sometimes dont seem to line up with the Fan Control.

For example:  One GPU will seem to run hotter than the average, and then there will be aonther GPU  that is colder than average.

So What I think is that as CGminer turns up the fan Rate to compensate for a hotter card  it actually turns up a fan on the wrong card, thus now you see the cooler temp on another card.

I have not found a solution for this yet.  beginning efforts with gpu mapping havent seemed to work for me yet, or I haven't mapped them correctly.

[Equate]

are you using risers ?

[rascal777]

not question for me, but I am using risers

[CryptoCluster]

@Equate: Some cards are on riser (not powered risers), and some are connected directly into the mainboard.
3rd slot card was tested both ways, but it does not change temp readings.

@rascal777: I have tried manually changing Fan speed to 100%, it does not help.


Today I have used IR thermometer, just in case only readings in GPU-Z and cgminer are wrong, but they are not...

[peonminer]

Does the card have a display plugged in? I have to run my display card lower than the rest.... Download CGWatcher and learn it. It'll save your rig when you're not around and even when you are.......................