cancel
Showing results for 
Search instead for 
Did you mean: 

Z690 Extreme / PCIEX 16X_1 lanes at 8x if I use M.2_1

simon_leuener
Level 10
As in the title, if I use
1 Graphic card in PCIEX 16x_1 and 1 M.2 in M.2_1
the Graphic lanes are reduced to 8x

If I insert my m.2 into m.2_2 I have the full 16x lanes on the graphic card.
Dont think the board is broken...

How would u every use the m.2 Gen 5 in m.2_1, if it halves the Graphic card lanes to 8x???
I dont understand ASUS, if this is a normal behaviour. Its a damn 1200EUR board

Should i set m.2 in m.2_1 and the Graphic card in the second slot PCIEX 16x_2?
What is a solution (beside get a new or another board lol)

Thanks for help everyone 🙂
861 Views
17 REPLIES 17

It also took me awhile to understand all the implications, but let me try to summarize it as follows:

If using a dedicated GPU graphics card:
- Use M.2_2 if using a PCIe 4.0 boot drive. It is linked to the CPU, allows the GPU to run at x16 on the first PCIe 5.0 expansion slot, and does not disable the second PCIe 5.0 expansion slot
- Use M.2_1 if using a PCIe 5.0 boot drive (in the future). It is linked to the CPU, but the GPU will run at x8 on first PCIe 5.0 expansion slot, and disables the second PCIe 5.0 expansion slot

If you're using integrated CPU graphics (where expansion slots don't matter):
- Use either M2_1 or M2.2 slot if using a PCIe 4.0 boot drive
- Use M.2_1 if using a PCIe 5.0 boot drive (in the future)

Corrections anyone?

Was just about to post about this and I saw this thread.

I have the ROG Maximus Z690 Extreme. It seems odd that for a thousand dollar mobo, you would be limited to use one high end feature or the other. Seems like for an "extreme" premium board, you should be able to take advantage of full PCIE 5.0 for the GPU, and full PCIE 5.0 for the NVMe.

I have a Samsung 980 Pro NVMe that I currently have installed in M.2_1, and a Strix 3090 in PCIEX16(G5)_1. I'm not using the second PCIEX16(G5)_2 slot for anything cuz I just won't need any other cards in my build.

Not seeing anywhere in the manual where it says that M.2_1 shares bandwidth with the PCIEX16(G5)_1 slot.

the only thing I see about bandwidth sharing is this "M.2_1shares bandwidth with PCIEX16(G5)_2. When M.2_1 is enabled, PCIEX16(G5)_2 will be disabled"
So I was under the impression that the only downside to having the M.2_1 slot occupied by an NVMe would be not being able to use PCIEX16(G5)_2.

I see a box that shows that PCIEX16(G5)_1 and PCIEX16(G5)_2 are reduced to 8X if you are using a dual VGA configuration, but nothing about M.2_1 affecting the first slot [PCIEX16(G5)_1].


Am I missing something? Is there documentation somewhere that says the M.2_1 and PCIEX16(G5)_1 are reduced to 8X if both are used?

New infos suggest that upcoming new RTX 4000 series GPU will be PCie Gen 4 only:

So if M.2_1 slot have a ssd on it, or the PCIE5_2 has an any PCIe card on it,
With a Pcie Gen 4 GPU we are limited to Pcie Gen4 x8 (16 GB/s Bandwidth) on the PCIE5_1 slot?

So we get only 16 GB/s Bandwidth for the GPU with the Asus z690 Extreme?
That is the same as PCie Gen3! it will bottleneck new GPU..

Why can't PCIE5_1 do Pcie Gen4 x16 (32 GB/s Bandwidth) with a Pcie Gen 4 GPU and using M.2_1 ?

Can this be fix with a Bios update?

rjbarker
Level 11
Extreme Board has 3 M.2 Slots right? Use M.2_2 and M.2_3 for 2 NVMe 4.0 Drives, this will ensure your single GPU in top PCI-E_1 slot runs at x16.....

Apex has two M.2 Slots, both can be occupied NVMe 4.0 w GPU running x16

Mangonz
Level 9
Yep, I agree with both posts.

The Apex it doesn't have a PCIe 5.0 M.2 on the board itself like the first M.2 on the Extreme. It's a PCIe addon card that would go in second PCIe x16 slot if needed in time (or if you just need more m.2 slots). I think you have to enable the setting for ReDriver in bios if you ever use it otherwise PCIe 5.0 would struggle to work through the expansion card without causing errors.

Wish i'd read this thread before building.

My 690 Extreme Board:
M.2_1 ------ Samsung 980 Pro (Boot / OS)
PCIe_1 ----- RTX 3070 Ti (all I could find)

Questions:
1. Should I move the Samsung 980 Pro to M.2_2 ?
2. Is it as simple as physically moving it, without any Bios adjustments?
3. Will it make a noticeable difference for 3070 Ti?

4. If OS Drive stays at M.2 . . . where should I add a 2nd drive?
5. If OS Drive moves . . . were should I put the OS Drive & the 2nd Drive?

Thanks in advance. . . . I'm getting out my depth.

AviatorIMC wrote:
Wish i'd read this thread before building.

My 690 Extreme Board:
M.2_1 ------ Samsung 980 Pro (Boot / OS)
PCIe_1 ----- RTX 3070 Ti (all I could find)

Questions:
1. Should I move the Samsung 980 Pro to M.2_2 ?
2. Is it as simple as physically moving it, without any Bios adjustments?
3. Will it make a noticeable difference for 3070 Ti?

4. If OS Drive stays at M.2 . . . where should I add a 2nd drive?
5. If OS Drive moves . . . were should I put the OS Drive & the 2nd Drive?

Thanks in advance. . . . I'm getting out my depth.


I have M_2 and M_3 populated with 980s. I left the M_1 slot open since there aren't any m_2 5.0's out there anyway. The M.2_1 shares the 16 PCIe 5.0 lanes with PCIE 1st slot and if you had a 5.0 m2 plugged in it would disable the second gpu slot. Honestly, imo it doesnt matter how you set it up.

Perceivably I don't think 16x or 8x 5.0 makes a difference gameplay-wise. PCEI 5.0 is 32gt/s, just for reference, at 16x full saturation its eating 128 gb/s and at 8x 64gb/s. PCIE 4.0 at 16x is equal to pcie5.0 at 8x. Soooo long story short, yes it will drop it to 8x. But at that bandwidth its irrelevant. I would move it to the second slot if it bugs you, I only left the 1st m2 slot open cuz im waiting for a 5.0 card to come out.


Thanks for the reply . . . all makes sense, from what i've seen.

I have read that a 1070 Ti will not likely reach saturation at 4.0 x 8 lanes anyway . . . but I haven't really been able to confirm. Thoughts?

if so, I'll likely just leave the 980 in the M.2_1 slot for now.