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PCIe Slot Configuration

kitfox

kitfox

Senior member
I'm getting ready to build a new z97 system. The system is going to be be air cooled with a large 140mm heatsink. The motherboard I had in mind was a Z97 OC Formula. The problem is, the cooler is not going to fit on the board with the graphics card in the top slot. If I move it to a different slot, will it still run at x16? Or are the other slots on these boards locked/capped at x4/x8?
 
I'd bet no. Most motherboards just look at the lowest slot with a card installed and split it up according to presets. (16, 16/8, 8/8/8, 8/8/4/4)

Board with PLX chips can be smarter than that though.

Slot behavior with different cards installed/configured will be in the manual, so that's where I'd look if I wanted to know for sure.

Even running at 8x isn't going to have a serious impact on anything though.
 
kitfox said:
I'm getting ready to build a new z97 system. The system is going to be be air cooled with a large 140mm heatsink. The motherboard I had in mind was a Z97 OC Formula. The problem is, the cooler is not going to fit on the board with the graphics card in the top slot. If I move it to a different slot, will it still run at x16? Or are the other slots on these boards locked/capped at x4/x8?
Click to expand...

What cooler do you plan to use, what cooler did you purchase for use, or what cooler are you using?
 
Haven't bought it yet, but probably a NH-U14S. I checked the pdf manual, I couldn't find anything that specifically that it'd run at full speed in any of the 3.0 slots. The specs page kind of implies it's only x16 in the first slot the way it's worded (PCIE1/PCIE2/PCIE4: single at x16 (PCIE1);)
 
kitfox said:
Haven't bought it yet, but probably a NH-U14S. I checked the pdf manual, I couldn't find anything that specifically that it'd run at full speed in any of the 3.0 slots. The specs page kind of implies it's only x16 in the first slot the way it's worded (PCIE1/PCIE2/PCIE4: single at x16 (PCIE1);)
Click to expand...

See, they are making it way more complicated than they need to:
- 3 x PCI Express 3.0 x16 Slots (PCIE1/PCIE2/PCIE4
- this says that all can run a single card at 16; but then it goes on to say:
- single at x16 (PCIE1); dual at x8 (PCIE1) / x8 (PCIE4); triple at x8 (PCIE1) / x4 (PCIE2) / x4 (PCIE4))
- in which they are tying it to a specific slot.

So they are saying it both ways, but according to Intel, the slot is not a chipset limitation:
http://www.intel.com/content/www/us/en/chipsets/performance-chipsets/z97-chipset-diagram.html
as there are three PCI Express 3.0 lanes available in the chipset.

In contrast, my Asus board says "2 x PCIe 3.0/2.0 x16 (Single at x16, dual at x8/x8)," for the first two slots and "1 x PCIe 2.0 x16 (max at x4 mode, black)" for the third slot, which makes it more clear about how it handles these slots.

However, since both boards use the same chipset, the first two slots on the Asrock may be similar to my Asus, and they are just wording it differently.

BUT the Asrock gets even more fun if you are using M.2, which bumps all lanes down to 8x.
Of course, as we've established, ASRock's Z97 Extreme6 is unique. It does have a two-lane M.2 PCI Express 2.0 slot competing for the PCH's limited bandwidth. But it also employs what ASRock calls Ultra M.2, which is a second slot tapping into a Haswell-based CPU's 16 lanes of third-gen PCIe, too. This slot isn't affected by the chipset. And if you drop a PCIe M.2 drive into the Ultra slot, you can still use SATA Express, which is wired into Z97. In exchange, you can't run a graphics card using the processor's 16 lanes, instead bumping it down to eight. Perhaps more severely, SLI and CrossFire configurations are out, too.
Click to expand...

http://www.tomshardware.com/reviews/samsung-xp941-z97-pci-express,3826-3.html
 
Ah thanks for clearing that up. I did not know that about the M.2 slot. Do you know if thats the same with every manufacture or is it just the way Asrock rigged it up?
 
PhIlLy ChEeSe said:
LOL@ tomshardware!
Click to expand...

Care to clarify that? ASFAIK the current Z97 boards from Asrock are regarded as some of the best for a bootable M.2. I think it is pretty much a given that future chipsets will be find a way through the current limitations.
 
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