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Graphics Card in Slot Other than 1 and 2

C

cdf

macrumors 68020
Original poster
Jul 27, 2012
2,258
2,587
I have a non-flashed EVGA (half-sized, PCI-powered) GTX 750 Ti, which I use to run my 4K display at 60 Hz. I currently have it installed in slot 3 of my 2009 cMP. I understand that there could be a performance hit if the card is not in a 16x slot (and I might have seen some minor screen artifacts), but I rarely use the GPU intensively. The card seems to work fine for my needs.

My concern is power. My graphics card is rated at 60 W. I know that the 16x slots can provide 75 W each, and I believe that the 4x slots can provide 25 W each. My question is: can the computer's logic board be damaged by having my card installed in slot 3?
 
666sheep said:
Nope. Your math (whatever it is) is wrong.
Click to expand...

Would you care to elaborate? Because there is no math here. The card is rated at 60 W. Most of the time it probably needs much less. So I assume that the 25 W of the 4x slot is sufficient. I'm just unsure what might happen when the card needs more than 25 W.
 
cdf said:
Would you care to elaborate? Because there is no math here. The card is rated at 60 W. Most of the time it probably needs much less. So I assume that the 25 W of the 4x slot is sufficient. I'm just unsure what might happen when the card needs more than 25 W.
Click to expand...

Pcie 2.0 carries 75w in each slots if they're 16x wide. The cards determine how much power they will draw, not the card slot.
 
Last edited:
That's a PCIe 2.0 x4 bandwidth slot with the ability to accommodate x16 card physically. In other words, they provide 75W each, but not share 25W for both slot 3 and 4.
 
Thanks for your responses. As I understand it, since all the slots are 16x mechanically, they are rated for at least 75 W each. So in my case there would be no problem. In fact, according to the official specifications (support.apple.com/kb/SP506), a slot may even exceed 75 W, because the combined maximum for all of them is 300 W.
 
Yup. We've had people here run 3 or even 4 GPU setups. The pcie power won't be you're issue.
 
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