Help Understanding Boost Clock on Nvidia 670

[Phinix]

I have two MSI 670 PE/OC cards in SLI.

According to the MSI website the card is meant to have a boost clock of 1097Mhz, but my one card boosts to 1228Mhz and the other to 1215Mhz.

I have done no Overclocking and have not changed a single setting in afterburner, not even the power limit.

In fact the one card that boosts to 1215Mhz is unstable at that speed and i have to down clock it, luckily i've qualified for a RMA on it since this is how it came.

Can someone explain to me why these cards are boosting so high? What influences their boosts clock?

[VladPhotoPro]

If you want very very detailed answer, you can find it here:

http://www.overclock.net/t/1265110/the-gtx-670-overclocking-master-guide#post_17391118

quick version:

GPU boost on 670, will boost your card, until you hit pre-set power consumption, or temperature, whichever comes first, and at that point will start down clocking itself in 13mhz steps. (temp over 70 C, power consumption over 100%)

So even small temperature difference between two cards can explain different clock speeds. Also one of the cards in SLI being main card can affect how close it is to power consumption limit, which also can down clock it.

To properly find out what is the answer in your situation, you will need monitoring software like MSI afterburner and you will have to see where you at on temperature and power consumption.