Why is my Gigabyte GTX460 Sli Fan speed different on two cards?

[shanghai_stin]

Hi, There

I have SLI setup with two Gigabyte GTX460OC-1G cards,
the performance boosted as expected. but the fan speed is reporting differently for the two cards.
 
Card 1 is ranging from 2100rpm at 40% to 3900rpm at 100%
Card 2 is ranging from 1600rpm at 40% to 3400rpm at 100%

Both ranges are exactly 1800rpm difference from 40%-100%

Does anyone know is this a faulty on the card? if so, which one is running at the right speed?
Or maybe other issues?

I have no O.C in my system.

Thanks in advance.
Regards,
DD

Sysinfo:

CPU: i7-950
MB: Asus X58 Sabertooth
RAM: 3*2G
GC: Gigabyte GTX460OC-1GB x2 in SLi

Nforce Driver Package version Not reported
Audio Driver 1.2.23.3
GART Driver Not reported
Graphics Driver 280.26 (8.17.12.8026)
Ethernet Driver Not reported
IDE Driver Not reported
nTune 6.05.26

========== Processor, Bus, and Memory Speed Information ==========

CPU Speed = 6352.199
CPU Multiplier = 1.000
FSB Frequency = 0
Memory Frequency = 0.000
AGP Frequency = 0

========== GeForce Information ==========

GPU 1: GeForce GTX 460
GPU 1 Video BIOS version: 70.04.1b.00.02
GPU 2: GeForce GTX 460
GPU 2 Video BIOS version: 70.04.1b.00.02

========== GPU's Core and Memory Speed Information ==========


GPU Core Speed = 715
GPU Memory Speed = 1800

GPU Shader Clock Speed = 1430


GPU Core Speed = 715
GPU Memory Speed = 1800

GPU Shader Clock Speed = 1430

GPU SLI Mode Enabled.

[Grozdan]

Higher RPM might me caused by a small space between the cards. To explain, upper card doesn't have enough space and air to cool itself as the lower one, so it must run at higher RPM to maintain the temperature. Lower card has much more space and air at its disposal so it runs at lower RPM...

Try removing the lower card completely and see if the RPM on the upper card goes down or switching the cards and see what happens. If currently upper card maintains higher RPM even though it's put in lower slot (or it's single), then you could try RMA because the lower one has usual RPM value (mine's at 1500RPM @ 40%) ...

This is nothing unusual - in SLI/Cross solutions, the upper card is always hotter and louder (higher RPM) than the lower one unless you can make some decent space between them or install watercooling...

[shanghai_stin]

Higher RPM might me caused by a small space between the cards. To explain, upper card doesn't have enough space and air to cool itself as the lower one, so it must run at higher RPM to maintain the temperature. Lower card has much more space and air at its disposal so it runs at lower RPM...

Try removing the lower card completely and see if the RPM on the upper card goes down or switching the cards and see what happens. If currently upper card maintains higher RPM even though it's put in lower slot (or it's single), then you could try RMA because the lower one has usual RPM value (mine's at 1500RPM @ 40%) ...

This is nothing unusual - in SLI/Cross solutions, the upper card is always hotter and louder (higher RPM) than the lower one unless you can make some decent space between them or install watercooling...

Thx Grozdan, Will try your suggestion.

[Grozdan]

No problem m8

Let us know if that solved your problem. If the upper card starts running at lower RPM then you don't have to worry about it because that's what happens in SLI/Cross.
These cards are are very silent even when fully stressed so little bit higher RPM wont disturb your "silence" and the temperatures will be similar for both cards which is the only factor (for me) that matters.
If you don't have any problems with your cards (crashes, restarts, BSODs, etc.) don't let higher RPM to prevent you from enjoying awesome combination of performance!

If the problem do persist, you could RMA just to be on the safe side...

[Dark Mantis]

Yes I think Grozdan is right in his diagnosis of why the top card's fan is going faster. As he says though it is not unusual at all. Watercooling is the best way to cool SLI or Crossfired cards.

[shanghai_stin]

No problem m8

Let us know if that solved your problem. If the upper card starts running at lower RPM then you don't have to worry about it because that's what happens in SLI/Cross.
These cards are are very silent even when fully stressed so little bit higher RPM wont disturb your "silence" and the temperatures will be similar for both cards which is the only factor (for me) that matters.
If you don't have any problems with your cards (crashes, restarts, BSODs, etc.) don't let higher RPM to prevent you from enjoying awesome combination of performance!

If the problem do persist, you could RMA just to be on the safe side...

Swapped the two cards, then they start to run at the same speed 1700rpm at 40%. I tried 5 minutes crysis 2, temp on the top card (was the slower rpm lower card) shoot up to 95c (old config with the extra fan speed kept the high temp at 87c). So I swapped them back to the initial config. The top card again runs 500rpm faster than the lower card.
Still didn't understand how is that happening but I decided to let it be this way, the extra 500rpm cools the top card effectively. As long as it's diaplying normal, I feel the 500rpm is needed.
thank you for all the help! I'll update this post again if anything strange happens.
Cheers

[Dark Mantis]

As you seem to have proved the card with the faster fan speed obviously requires the extra fan speed to keep the chip cool. For whatever reason that it is hotter the software has determined that it needs to be ramped up to cope and that is what is happening.