DOES ASROCK PLAY A LITTLE DIRTY?

[caddi daddi]

I use an asrock extreme 9 Z97 board.
a bit ago I got A Sammy 960 evo NVMe drive, gen 3x4.
got it in and the os migrated over and boy is it fast.
I decided to reinstall my second gpu and to my great unhappiness the rig suddenly will not boot, so I pop into bios to have a look around and find my Sammy boot drive missing from boot order, I see both graphics cards and even my m.2 sata drive, UH,OH

shut it down, pull the second card and it boots right up.
grab my manual to check where the second card goes and it says slot pcie4, right where I had put it so I shut down again and reinstall the gpu back in slot pcie4 and swap power cables from one gpu to the other, put it all back together and try to boot up again, it's still a no go, so I boot to bios and the 960 sammy is not shown anywhere but both gpu's show up just fine, uh, oh
pull it back out again, grab the manual and check where else the second card can go, pcie slot 5 looks to be the next place, but, it's not going there, that's where all the front panel connecters are and the card will not slide all the way into the slot. where to next?
pcie slot 2, right where it will cut all the air off to the card in slot 1 but, hey let's try it shall we.
yes, it boots right up and both cards show up in gpu-z with card 1 running at 87c under heaven benchmark.........
so what I can't find anywhere from asrock is that pcie4 is turned off when you install an NVMe drive in the ultra m.2 connecter........
I love my hobby!!!!!!!!!

 

[JrClocker]

You can get yourself a PCIe m.2 adapter!

 

[Lochekey]

This is common on a lot of boards to have shared lanes somewhere. My boards(Maximus Gene VIII) M.2 shares lanes with the #1 and #2 sata port and disables them if I have an M2 drive installed.

 

[dejo]

and if you use the hyper m.2 pcie board it disables 2 more on that maximus viii gene

 

[Alaric]

Sounds like a shortage of PCIe lanes. It looks like Intel's reliance on faster PCIe 3.0 and fewer lanes is starting to bite them in the hindquarters. Another example of AMD getting something ahead of the curve and falling behind before it's really useful.

 

[Woomack]

For 2 or 3 generations nothing has changed in pcie lanes count ( at least for end user ) but we got additional slots. Every motherboard without PLX is disabling one or more pcie slots when you use M.2 pcie drive. On X99 motherboards with more than 1 M.2 slot you have to use 40 lane CPU to use all PCIE and M.2 slots.
On the other hand PCIE SSD are not really much faster for games etc. People see high bandwidth and think it will be so great while most tasks are finishing as fast on SATA as on PCIE SSD ( at least general user experience not looking at bandwidth etc ). General performance of better PCIE SSD is like 4xSATA SSD in RAID0. Still random operations are not so much better than SATA SSD.

 

[caddi daddi]

just be nice for them to say, SOMEPLACE, that you give up pcie4 for nvme so you could plan a little.
Asrock was able to tell me what I have to give up to run m.2 sata but, nothing about what I give up for the nvme slot.........

 

[Woomack]

Almost all motherboards are the same. If you have 16/8 + 16/8 + 4/1 PCIE slots then almost always 4/1 won't be available when you use M.2 slot. In some cases like on micro ATX boards part of SATA ports won't work when you use PCIE SSD in M.2 slot but they let you to use pcie x4 slot in x1 mode or x1 slot if there is no x4.
Regardless what is motherboard brand, all are about the same.

Simply there are 24 pcie lanes to split. 2x pcie 8 = 16 and there are 8 left so what can you do with that ? M.2 PCIE = 4 lanes ( or mentioned x4 pcie slot ). SATA and other controllers take part of them and for some reason I feel like there are always some unused lanes.

Z97 and Z170 motherboards have almost the same slot/port settings while Skylake has more pcie lanes ... this I don't really understand as some motherboards like Z170 OC Formula support 3x M.2 PCIE slots and still support all other devices while some other motherboards have these limitations regarding slots even though are based on the same chipset.

 

[dejo]

I have 2 samsung 960 pro 256gb nvme drives and when in raid0 they are way slower on the small reads and writes than when loaded as standard ahci