PCI-E CPU lanes explained I need some help

  • Thread starter Deleted member 362816
  • Start date
Toggle sidebar Toggle sidebar
D

Deleted member 362816

Guest
My build is listed in my sig.

I know very little about how this works and I am trying to figure it out.

I know the z170 chip set has some of its own lanes.

So with dual fury x video cards and a pci-3 x4 t8e network card am I bottle-necking anything?

If not can I add 1 more pcie x4 card for more usb 3.0's
 
Solution
Supernova1138


In theory, 1, in practice regarding the M.2 slot, some boards do allow the M.2 slot to only take 2 PCI-E lanes and run at a reduced maximum speed of 10Gbps, which can allow for SATA devices to use the SATA Express port as well. I'm not 100% sure if that would also allow the PCI-E slot to work as well at X2 mode, you would have to consult your board's manual.
Sort by date Sort by votes
T

TJ Hooker

Titan
Ambassador
Apr 15, 2014
11,474
1,622
72,390
You should be fine. Both GPUs will be running on x8 connections direct to the CPU, which has negligible effect compared to x16. I thought most network cards were only x1, but regardless it'll be using x4 through the chipset, so again that's fine.

The connection between the chipset and CPU is only PCIe x4 speeds, so technically if you were to install another x4 card and max out USB reads/writes and network activity at the same time, you would in theory bottleneck. Realistically, I wouldn't worry about it.
 
Upvote 0 Downvote
D

Deleted member 362816

Guest


Ok thought I understood technology I guess I don't.

So I need to maintain x8/x8 on my dual gpu's at all times.

What makes one card run off the chipset and another run off the cpu? Do the gpu's always pull fromt he cpu and add on cards network/usb etc pull from chipset on z170.

So on my build if I am running

Fury X
Fury X
Tp-Link T8E ac 1750 Network
Rosewill Usb 3.0 usb pci-e card

Will I have no issues?
 
Upvote 0 Downvote
Supernova1138

Supernova1138

Illustrious
Mar 22, 2011
5,340
54
37,690
For Skylake CPUs you get 16 PCI-E lanes, which can be divided into an x8 x8 configuration for SLI or Crossfire on Z170 motherboards, those would be the top two full sized PCI-E x16 slots on your board. All your other PCI-E slots take lanes off the chipset. The network card wouldn't cause a PCI-E bottleneck, however adding an additional PCI-E x4 card will not be possible, as your board only has a single PCI-E x16 slot at x4 speed coming off the chipset. The other PCI-E slots only offer a single lane. If you want more USB 3.0, you'd have to either get a PCI-E x1 USB 3.0 card, or ditch the network card.
 
Upvote 0 Downvote
D

Deleted member 362816

Guest


I am running the network card off pcie1x1 lol just noticed that.

I seem to be getting good performance is there a need to move it to the x4?
 
Upvote 0 Downvote
D

Deleted member 362816

Guest
Š 1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot shares bandwidth with the M2H_32G connector. The PCIEX4 slot
will become unavailable when an SSD is installed in the M2H_32G connector

So If I install a M2 SSD I lose this slot?
 
Upvote 0 Downvote
Supernova1138

Supernova1138

Illustrious
Mar 22, 2011
5,340
54
37,690


You don't need to move the network card if it's giving you decent performance, it might technically be a bottleneck if you saturate your network to full 802.11ac speeds, but I doubt you have an internet connection fast enough to do that, few people do. You could put the USB 3.0 card into the 3rd full size PCI-E slot. As the specs say, that slot shares PCI-E lanes with the M.2 port, so if you get an M.2 SSD later on, you will lose that PCI-E slot.

You seem to be one of the few people who would benefit from the X99 platform and its larger number of PCI-E lanes given the number of expansion cards you want to use.
 
Upvote 0 Downvote
D

Deleted member 362816

Guest


I almost bought the x99 with a 5820 but no I did this instead should have spent the extra 150$
 
Upvote 0 Downvote
Supernova1138

Supernova1138

Illustrious
Mar 22, 2011
5,340
54
37,690


In theory, 1, in practice regarding the M.2 slot, some boards do allow the M.2 slot to only take 2 PCI-E lanes and run at a reduced maximum speed of 10Gbps, which can allow for SATA devices to use the SATA Express port as well. I'm not 100% sure if that would also allow the PCI-E slot to work as well at X2 mode, you would have to consult your board's manual.
 
Upvote 0 Downvote
Solution
D

Deleted member 362816

Guest


Thanks so much for the help.

I might move to a x99 with a 6800k. Would give me more breathing room.
 
Upvote 0 Downvote
T

TJ Hooker

Titan
Ambassador
Apr 15, 2014
11,474
1,622
72,390

No, it would be pointless, the card would still only run at x1 anyway. A PCIe 3.0 x1 connection provides 1 GB/s bandwidth (8 Gbps), there's no consumer grade network card available that could saturate that.


SATA connections don't seem to share bandwidth with other connections, don't think they'd be affected by adding an M.2 or whatnot

Yes, in theory the OP could benefit from X99, but it would be a bunch of money for little benefit in my opinion.
 
Upvote 0 Downvote
Supernova1138

Supernova1138

Illustrious
Mar 22, 2011
5,340
54
37,690


On Z170 boards the six SATA ports tend to be four regular SATA ports and a SATA Express port that can be used as two regular SATA ports. The SATA Express port and M.2 slot share PCI-E lanes, so if you do use those additional SATA connections or use a SATA SSD in M.2 form factor, the OP would at minimum lose some bandwidth on the PCI-E x4 slot.
 
Upvote 0 Downvote
T

TJ Hooker

Titan
Ambassador
Apr 15, 2014
11,474
1,622
72,390

Good point, you're right they do share bandwidth.
Looking at the manual, there's one M.2 slot that shares bandwidth with the PCIe x4 slot, and a 2nd M.2 slot that shares bandwidth with the SATA (Express) ports. So you're able to populate the x4 slot, one of the M.2 slots, have both run at full speed, but you'd be down to 2 SATA ports. Although, having 1 M.2 SSD, a SATA HDD, and then either a optical drive or 2nd HDD seems like enough for most people.

 
Upvote 0 Downvote
You must log in or register to reply here.

TRENDING THREADS

Latest posts

Moderators online

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom