Originally Posted by wirk
Can somebody enlighten me in the following? Are the any differences in overclocking possibilities between a single dual GPU card and two single cards with the same GPU? What I mean is that dual GPU card gets power from a single PCIe slot. PCie slot is limited to 75W of power which has to be divided between the both GPUs while in the case of two cards each GPU can get 75W of power. Similar thing is additional power connectors on the cards, Titan Z has two 8-pin connectors which are rated 120 W each for the total of 240 W. This brings total rated power consumption for the Titan Z at 315 W. For the single GPU card with 8-pin and 6-pin connectors their rated power is 200 W and total power for single card is 275W. For two cards the power is 550W which is much higher than the 315 W for a dual GPU card. We can assume of course that total power supplied can be higher than that but there are limits on this.
The question thus is: Is there any limitation on overclocking the dual GPU card due to limitation on the power supply as compared to two single GPU cards?
For concrete example: I have two Titan X SLI watercooled with overclocking at 1505 MHz. The cards consume then between 350-400 W each peak which gives 750-800 W for both. If there would be dual GPU card with Titan X chips it seems to me it would be impossible to provide it with the equivalent power and thus its overclocking range would be limited
by the total power which can be delivered to a single card. Is this true?
The titan z = 375w and 2x 8pins from the spec sheet on the nvidia website which makes it a 375w solution vs the 250w solution of a normal titan.
The reason these cards exist is for people with only 1 pci-e slot / lack of connectors for whatever reason / lack of space.
The titan z will downclock also the moment it pushes past he 375w or when it heats up to much.
So to answer your question, yes they are limited not only by heat output ( which can be fixed through water cooling ) but also through power limitations. Reason why people didn't bought this card.
Reason why people bought 295x2 was because of it's free watercooling and still get great performance for a solid price ( when the price lowered ). ( while the 290's where junk at the start ).
Titan x = 8 pin + 6 pin = 300w
Titan x (x2) = 8 pin + 8 pin + 8 pin + 6 pin = 600w.
But then there are different versions of titan x, i believe there even are water cooled 4x 8 pin versions.
So yes dual gpu solutions will always stay inferior, even while you can water cool to get rid of the heat on dual gpu cards. A single card will cool better on it's own watercool solution and therefore also gain more gains.