SLI not running at x16 and x8

[txaggie2011]

I just SLI'd my EVGA GTX 970 with an identical 970. they're plugged into the x16 and x8 slots of my gigabyte GA-Z77X-UD5H mobo, but GPU-Z is reporting one card being on x8 and one on x4. is this normal or is there something wonky going on in the system?

From what I can tell, the PCIeX16 X8 and X4 are on their own bus tied directly into the CPU. the other PCIeX1 slots are handled directly by the Z77 chipset. I have a SATA card to add more HDDs on that bus, but if I'm looking at the block diagrams correctly, that shouldn't be affecting the GPU slots at all.

Is there any particular reason why the 2 GPUs are only reporting x8 and x4 instead of 2 x8's?

 

[jdog2pt0]

Motherboard limitation. On the specifications page it says this

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot is available only when an Intel 22nm (Ivy Bridge) CPU is installed.
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode

I'm guessing you have a network card, or maybe a sound card installed as well?
Here's the page I got the info from https://www.gigabyte.com/Motherboard/GA-Z77X-UD5H-rev-10#sp

 

[txaggie2011]

Motherboard limitation. On the specifications page it says this

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot is available only when an Intel 22nm (Ivy Bridge) CPU is installed.
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode

I'm guessing you have a network card, or maybe a sound card installed as well?
Here's the page I got the info from https://www.gigabyte.com/Motherboard/GA-Z77X-UD5H-rev-10#sp

Nope. Nothing on the x4 spot. Just a sata card in the first pciex1 slot. And the CPU is a 3xxx series, which I thought was ivy bridge.

 

[jdog2pt0]

Motherboard limitation. On the specifications page it says this

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot is available only when an Intel 22nm (Ivy Bridge) CPU is installed.
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode

I'm guessing you have a network card, or maybe a sound card installed as well?
Here's the page I got the info from https://www.gigabyte.com/Motherboard/GA-Z77X-UD5H-rev-10#sp

Nope. Nothing on the x4 spot. Just a sata card in the first pciex1 slot. And the CPU is a 3xxx series, which I thought was ivy bridge.

Anything in the M.2 slot? Also, if you remove the second card, what does GPU-Z report your card running as then?

 

[txaggie2011]

Motherboard limitation. On the specifications page it says this

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot is available only when an Intel 22nm (Ivy Bridge) CPU is installed.
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode

I'm guessing you have a network card, or maybe a sound card installed as well?
Here's the page I got the info from https://www.gigabyte.com/Motherboard/GA-Z77X-UD5H-rev-10#sp

Nope. Nothing on the x4 spot. Just a sata card in the first pciex1 slot. And the CPU is a 3xxx series, which I thought was ivy bridge.

Anything in the M.2 slot? Also, if you remove the second card, what does GPU-Z report your card running as then?

No, nothing on the mSATA, but every other SATA slot (0-8) is populated. As for what it reads with only one card in, I'm not entirely sure. I'll try pulling it out a little later today and I'll report back on what it shows.

 

[txaggie2011]

Motherboard limitation. On the specifications page it says this

1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot is available only when an Intel 22nm (Ivy Bridge) CPU is installed.
* The PCIEX4 slot shares bandwidth with the PCIEX8 and PCIEX16 slots. When the PCIEX4 slot is populated, the PCIEX16 slot will operate at up to x8 mode and the PCIEX8 will operate at up to x4 mode

I'm guessing you have a network card, or maybe a sound card installed as well?
Here's the page I got the info from https://www.gigabyte.com/Motherboard/GA-Z77X-UD5H-rev-10#sp

Nope. Nothing on the x4 spot. Just a sata card in the first pciex1 slot. And the CPU is a 3xxx series, which I thought was ivy bridge.

Anything in the M.2 slot? Also, if you remove the second card, what does GPU-Z report your card running as then?

Okay I finally had a chance to remove the second card and check GPU-Z. it appears the main card in the x16 slot is still running at x4. https://imgur.com/a/4ypwv

I double checked. the processors an ivy bridge 3570k, and theres absolutely nothing on the mSATA and the only other thing plugged in on the boards PCI slots is a SATA card on the first PCIeX1, which the manual says is on a completely different branch from the PCIeX16 x8 and x4, which should mean its not interfering with it. What else could possibly be causing the cards not to use all the PCI lanes?

If it helps any, heres the full spec sheet on the rig:
mobo: gigabyte GA-ZyyX-UD5H
CPU: intel i5-3570k ivy bridge
GPUs: EVGA GTX 970 (04G-P4-3975-KR)
RAM: 2 Patriot 8GB 1600MHz sticks and 2 gskil ripjaw 4GB 1600MHz
1 SATA expansion card on PCIEx1
and every SATA port (on the expansion card and mobo, save for the M.2 connection) is populated by various hard drives SSD's and one optical drive

 

[delta5]

You don't need x16 or x8 for a 970. I forget the website but even with a 1080/1080ti x8 verse x16 is less than 1% hit.

 

[txaggie2011]

You don't need x16 or x8 for a 970. I forget the website but even with a 1080/1080ti x8 verse x16 is less than 1% hit.

Thats definitely good to know, thank you for that. Still though, I'm curious why it isn't showing the correct x8/x8 or single x16 like it should. Realistically, nothing else I have jammed in that machine should be using any of those 16 lanes except the cards themselves.

 

[jdog2pt0]

It is possible that GPU-Z is reporting wrong. Those programs aren't perfect, and every motherboard is different. Could try seeing if there is a BIOS update for your board, and/or newer chipset drivers as well.

 

[txaggie2011]

It is possible that GPU-Z is reporting wrong. Those programs aren't perfect, and every motherboard is different. Could try seeing if there is a BIOS update for your board, and/or newer chipset drivers as well.

I think you're right. could just be a screw up on GPU-Z's part. no new BIOS updates or chipset updates.

 

[jdog2pt0]

It is possible that GPU-Z is reporting wrong. Those programs aren't perfect, and every motherboard is different. Could try seeing if there is a BIOS update for your board, and/or newer chipset drivers as well.

I think you're right. could just be a screw up on GPU-Z's part. no new BIOS updates or chipset updates.

I read somewhere that, at idle, the computer/card may conserve power by narrowing down the lanes used. I don't know if there's any merit to that, but maybe get a game going, and check GPU-Z while the game is going?

 

[txaggie2011]

It is possible that GPU-Z is reporting wrong. Those programs aren't perfect, and every motherboard is different. Could try seeing if there is a BIOS update for your board, and/or newer chipset drivers as well.

I think you're right. could just be a screw up on GPU-Z's part. no new BIOS updates or chipset updates.

I read somewhere that, at idle, the computer/card may conserve power by narrowing down the lanes used. I don't know if there's any merit to that, but maybe get a game going, and check GPU-Z while the game is going?

I read some of the same things you did. I checked it with furmark going so the GPUs were under full load and with a couple games. no change in the number of PCI lanes. the only thign that changes was the 1.0/2.0/3.0 appended to the end of the x8 or x4

 

[txaggie2011]

I checked a few other programs other than GPU-Z. Speccy Pro reports the same x8/x4 As does the GPU monitoring option in OC Scanner X from EVGA... I'm going to try to start unplugging other peripherals to see if this corrects the issue. I know the system diagram states the PCIEx1 slots are all entirely on the Z77 south bridge and aren't part of the PCIEx16 lanes handled directly by the CPU, but I'm wondering if that SATA card in the slot might be hogging lanes. Figured I'd unplug that and 10 of the 13 hard drives / SSDs that I have in there. I'll update when I find out more.

 

[jdog2pt0]

13 drives? Man, I thought I had a few with just 3. Kinda jealous to be honest.

 

[txaggie2011]

13 drives? Man, I thought I had a few with just 3. Kinda jealous to be honest.

lol thanks.. It's a bit of a problem for me. I'm a bit of a content hoarder I've been slowly trying to upgrade the lower capacity drives to higher ones so I can consolidate older ones onto them and take up less space and power. Just this christmas I was finally able to copy over and remove a 1TB seagate that was manufactured in 2007 and has been reliably running (error free luckily) almost 24/7 since then to a new 4TB along with another 1.5TB drive as well.

 

[jdog2pt0]

13 drives? Man, I thought I had a few with just 3. Kinda jealous to be honest.

lol thanks.. It's a bit of a problem for me. I'm a bit of a content hoarder I've been slowly trying to upgrade the lower capacity drives to higher ones so I can consolidate older ones onto them and take up less space and power. Just this christmas I was finally able to copy over and remove a 1TB seagate that was manufactured in 2007 and has been reliably running (error free luckily) almost 24/7 since then to a new 4TB along with another 1.5TB drive as well.

At that point, I personally would look into (funds allowing) setting up a NAS/Server of sorts, and keep my rig to the only amount necessary to play games.

 

[txaggie2011]

13 drives? Man, I thought I had a few with just 3. Kinda jealous to be honest.

lol thanks.. It's a bit of a problem for me. I'm a bit of a content hoarder I've been slowly trying to upgrade the lower capacity drives to higher ones so I can consolidate older ones onto them and take up less space and power. Just this christmas I was finally able to copy over and remove a 1TB seagate that was manufactured in 2007 and has been reliably running (error free luckily) almost 24/7 since then to a new 4TB along with another 1.5TB drive as well.

At that point, I personally would look into (funds allowing) setting up a NAS/Server of sorts, and keep my rig to the only amount necessary to play games.

I've been meaning to do that for a bit.. I've actually got my first custom build entirely intact right now and just haven't found the time to shuffle files around and set it up in a good RAID setup for a server.

As for unplugging everything, I removed the PCI SATA card and unhooked every single hard drive save for the SSD that the OS is on. no change in it reporting x8/x4. I'm officially out of ideas on why it might be doing that.

 

[jdog2pt0]

Swap the cards, so the other one is in the top slot, and the one you had in is out of the computer. Check GPU-Z, if no change click the ? next to where it list what you're running at, and run the render test. See if there's any change in the listed speed.