PCIe x16 slots

JohnJSal

JohnJSal

Active Member
What is meant when the specs of a mobo say something like this:

2 PCI Express X16 slot(x16, x4)

or

1 x PCI-E X16, 1 x PCI-E X16 (x4 bandwidth)

as opposed to just saying it has 2 x16 slots? Is there a difference in one of the slots when the above is listed? Does it affect dual GPU performance?
 
Yeah... it means the slot is limited to x4 performance when both slots are used. So yes, it probably would affect the performance and you do not want that if you plan on using two cards.
 
oregon said:
Yeah... it means the slot is limited to x4 performance when both slots are used. So yes, it probably would affect the performance and you do not want that if you plan on using two cards.
Click to expand...

Thanks. So if only one slot is used, would either of them run at x16 (or do you have to use the "proper" one)? Also, if both are used, but not for SLI/CrossFire, do they both run at x16?
 
I'm assuming either would, but I don't know. It probably depends on the board.

I'd assume if both are used either one or both would run at x4. I don't know whether using crossfire/sli or not would make a difference.
 
oregon said:
I'm assuming either would, but I don't know. It probably depends on the board.

I'd assume if both are used either one or both would run at x4. I don't know whether using crossfire/sli or not would make a difference.
Click to expand...

Well, it sounds like something I might want to stay away from anyway. Good to know it does mean something different than normal. :)
 
It means the primary slot runs at x16 speed, however the second slot is physically a PCI-E x16 slot, however only provides the bandwidth of a 4x slot.
 
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