B450 Pro4 PCIe conflict

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   Hi, I have a problem with dual GPUs and nvme ssd in M2_2, it seems PCIE4 GPU conflicts with M2_2 nvme ssd.

I had a pin-misdefined ssd(cant be recognized in M2_1), so I can only mount it into M2_2 with bios setting 'Force nvme for M2_2 Slot'. With one GPU mounted in PCIE2(3.0 x16), everything ran smoothly. Then I bought another GPU and mounted it into PCIE4(3.0 x4), found that Windows can't recognize the PCIE4 GPU. That was strange, as M2_2 has nothing related to PCIE4(which shares lanes with M2_1), as M2_2 shares lanes with sata3_3 and sata3_4.

Then I tried turning off 'Force nvme for M2_2 Slot', not even removing ssd from M2_2, just rebooted(yes, this nvme ssd not showing in bios), booted another windows from ssd in sata3 slot, PCIE4 GPU showed in Taskmgr. Quite strange... so, any suggestion?

CPU: R7 5700X
MB: B450 Pro4, P10.43 beta(latest version)
RAM: 32GB DDR4 3200
SSD: Kioxia EXCERIA PLUS G3

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gordenf Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Feb 2026 Status: Offline Points: 30	Post Options Post Reply Quote gordenf Report Post Thanks(0) Quote Reply Topic: B450 Pro4 PCIe conflict Posted: 14 Feb 2026 at 7:47pm
	Hi, I have a problem with dual GPUs and nvme ssd in M2_2, it seems PCIE4 GPU conflicts with M2_2 nvme ssd. I had a pin-misdefined ssd(cant be recognized in M2_1), so I can only mount it into M2_2 with bios setting 'Force nvme for M2_2 Slot'. With one GPU mounted in PCIE2(3.0 x16), everything ran smoothly. Then I bought another GPU and mounted it into PCIE4(3.0 x4), found that Windows can't recognize the PCIE4 GPU. That was strange, as M2_2 has nothing related to PCIE4(which shares lanes with M2_1), as M2_2 shares lanes with sata3_3 and sata3_4. Then I tried turning off 'Force nvme for M2_2 Slot', not even removing ssd from M2_2, just rebooted(yes, this nvme ssd not showing in bios), booted another windows from ssd in sata3 slot, PCIE4 GPU showed in Taskmgr. Quite strange... so, any suggestion? CPU: R7 5700X MB: B450 Pro4, P10.43 beta(latest version) RAM: 32GB DDR4 3200 SSD: Kioxia EXCERIA PLUS G3

Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 34248	Post Options Post Reply Quote Xaltar Report Post Thanks(0) Quote Reply Posted: 16 Feb 2026 at 4:22pm
	I would guess that the setting to force NVMe for M2_2 disables the PCIe4 slot. NVMe uses 4 lanes where SATA3_3/4 only utilize a single lane between them. By forcing NVMe on M2_2 the other lanes need to be taken from the PCIe slot. You can open a support ticket and ask ASRock for a more definitive answer but based on your description that is what's happening.


gordenf Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Feb 2026 Status: Offline Points: 30	Post Options Post Reply Quote gordenf Report Post Thanks(0) Quote Reply Posted: 21 Feb 2026 at 2:27pm
	ahhh thanks! I checked the manual again, M2_2 uses 3.0x2，not 2.0x2 from chipset(as lanes of shared SATA was from chipset, so I only thought about chipset), and it all makes sense...M2_1, PCIE4, M2_2(NVME) share lanes.

garagedrive Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 5 hours 52 minutes ago Status: Offline Points: 30	Post Options Post Reply Quote garagedrive Report Post Thanks(0) Quote Reply Posted: 5 hours 42 minutes ago at 2:34pm
	M2_2 uses only 2 lanes (3.0x2), so, SATA3_3 & 3_4 lanes sharing with M2_2 (3.0x2) make sense. 4th PCIe slot uses 4 lanes, so, PCIe 4th lanes sharing with M2_1 (3.0x4) make sense. I have the same problem (BIOS 10.43) when using PCIe 4-NVME conversion card. Can anyone solve this issue? I think it can be fixed by updating BIOS.

Xaltar Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 16 May 2015 Location: Europe Status: Offline Points: 34248	Post Options Post Reply Quote Xaltar Report Post Thanks(0) Quote Reply Posted: 5 hours 35 minutes ago at 2:41pm
	That is something you would have to ask ASRock tech support directly: https://tw.asrock.com/events/tsd.asp


garagedrive Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 5 hours 52 minutes ago Status: Offline Points: 30	Post Options Post Reply Quote garagedrive Report Post Thanks(0) Quote Reply Posted: 5 hours 11 minutes ago at 3:05pm
	Now I see your point. M2_2 uses PCIe 3.0x2 from CPU, not PCIe 2.0x2 from B450 chipset. Lanes from CPU needs to be shared when utilizing M2_2. Thank you!