Ok, just to clarify a statement that I made concerning Z170 or Z97 chipset equipped Intel boards (this also goes for the earlier mainstream variants back thru to Z68\P67)........................
But since the Z170 or Z97 chipsets only show a total of 16 PCI-E 3.x lanes wired direct to CPU on the process maps that means that the rest of the PCI-E lanes are going thru the chipset itself, even the M.2 slots (this is very true for Z97, haven't quite figured this out for Z170 but looks to be the same) & then up the serial DMI link to the CPU.
Since I'm only gonna use 1 vid card that fixes 1 issue, but if you install any other PCI-E device in any other x16 slot (doesn't have to be a vid card) you will cause the 1st x16 slot to switch to x8 lanes, regardless.
According to Intel, the 16 PCI-E lanes (whether 1.x, 2.x or 3.x) that are wired to the CPU are also wired to the PCI-E x16 slots on the mobo as this was to facilitate SLI\Crossfire PCI-E vid card configurations up to 3-way SLI\Crossfire. Here is the breakdown as laid out by Intel:
What I was referring to in my statement above is concerning the usage of 1 PCI-E x16 vid card in a x16 slot & a PCI-E device that is NOT a x16 slot device (such as a sound card, LAN, WAP, PCI-E SSD on add-in riser card, PCI-E expansion cards, etc. are usually PCI-E x1, x2 or x4 slot or lanes if you prefer) in any of the other x16 PCI-E slots on the mobo will cause the PCI-E x16 vid card in a x16 slot to lose half of the available lanes (cut to x8 from x16) & the remaining available CPU wired PCI-E lanes outside of the lanes that the other PCI-E device used in the 2nd or 3rd x16 slot will become unused & wasted as these lanes are assigned\divided according to the number of x16 slots being populated on the mobo unless otherwise stated............. If the PCI-E device that is not a x16 slot device but has 8 lanes or is x8 spec'd (such as a PCI-E SSD on a PCI-E x8 riser card) is used in a 2nd x16 slot w/ a PCI-E x16 vid card in the 1st x16 slot then there will be no unused CPU wired PCI-E lanes as the lanes will be x8 on both of the x16 slots anyway......unless you put another PCI-E device in the 3rd x16 slot (if available) then you will cut the lanes in the 2nd x16 slot from x8 to x4 & the 3rd x16 slot to x4...............can cause a lane reduction to a PCI-E device(s) other than a 3-way SLI\Crossfire setup (if doing this you should already know this is going to occur) if not thought\planned out...............
The other PCI-E slots on the mobo that are not physical x16 slots are wired thru the chipset & the chipset assigns those according to the PCI device specs that the chipset reads from the device in the slot.......
These chipsets were the main reason why the advent of the M.2 slot for PCI-E SSD's starting w/ Z97 forward as this slot is wired thru the chipset's available PCI-E lanes which allows you to maintain the x16 slots wired direct to the 16 CPU PCI-E lanes to access system mem for the vid card(s) & still have direct PCI-E lane access to system mem for the PCI-E SSD\other PCI-E devices thru the serial DMI link.....
Where this is important to know is when you're deciding between using a mini-ITX mobo or microATX mobo or full size ATX mobo w/ these chipsets on them & what PCI-E devices & how many of them you want to use on said mobo due to the number of available slot type & size. If you want your single PCI-E x16 vid card to have the full 16 CPU wired PCI-E lanes you will need to know this to know what PCI-E devices you want & which PCI-E slots to put them in.....
In my statement above I was referring to installing a PCI-E SSD mounted on a riser PCI-E card on an Asus Maximus VIII ROG Z170 or Maximus VII ROG Z97 chipset microATX mobo which only has 2 x16 PCI-E slots, 1 PCI-E x4 slot & a M.2 PCI-E slot......putting this PCI-E x2 card in the 2nd x16 slot on these mobos would cut the 1st x16 PCI-E slot (where the PCI-E x16 vid card would be in) from x16 to x8 (lost 1\2 of total PCI-E bandwidth to vid card) then 6 PCI-E CPU-wired lanes would have been rendered useless & wasted in the 2nd x16 slot (device only needed 2 lanes or x2 of the available 8 lanes or x8).........not a good thing to do IMHO.............. Can it work this way, yep it can if you don't care about giving up potentially needed direct PCI-E bandwidth to system mem & the issues this may cause at some point.................. If I remove the M.2 SSD from the riser card & put it in the M.2 slot OR revert to SATAIII SSD on these mobos then I avert the potential CPU PCI-E lane loss issue entirely......which is a good thing IMHO as well...........
Hopefully this helps to clear up any confusion due to my statement given in earlier posting.
Now if this doesn't matter to anyone then please do what you will.....................the consequences of those decisions will be yours as well.............
