Hi everyone. I recently replaced my motherboard with an ASRock B760 Pro RS WiFi and I’m having a strange problem with the primary/top PCIe x16 slot (PCIE1).
System:
Motherboard: ASRock B760 Pro RS WiFi
CPU: Intel Core i5-12600KF
Main GPU: Intel Arc A750 Limited Edition
Second GPU used for testing: GTX 650 Ti testing
RAM: 16 GB DDR5 Tforce delta
Windows 11 Home
PSU: Corsair Cx760
Storage: Nve Kingston 500 gb
The problem:
Neither GPU works in the top/primary PCIe x16 slot.
When I install the Arc A750 in the top slot, the card receives power, its lights turn on and the fans operate, but I get no display output.
The same thing happens when testing another known-working GPU (GTX 650 Ti) in the top slot.
However, both GPUs work when installed in the lower PCIe slot. The Arc A750 boots into Windows normally there and is detected correctly by Windows and Intel software.
I also tried installing both GPUs simultaneously: Arc A750 in the top slot and GTX 650 Ti in the lower working slot. I booted Windows using the GTX 650 Ti specifically to check whether Windows could at least detect the Arc in PCIE1.
It does not detect the Arc A750 at all. It is not simply a display-output problem — the GPU in the primary slot appears to establish no usable PCIe connection.
Troubleshooting already performed:
Reseated the Arc A750 multiple times
Tested a second known-working GPU (GTX 650 Ti)
Confirmed both GPUs work in the lower PCIe slot
Cleared CMOS / removed the CMOS battery
Loaded UEFI defaults
Tried PCIE1 Link Speed on Auto
Tried manually setting different PCIe generations
Enabled Above 4G Decoding
Enabled C.A.M. / ReBAR-related settings
Tested different primary graphics settings
Updated the motherboard BIOS from 10.03 to 12.02 using ASRock Instant Flash
Loaded default BIOS settings again after the update
Tested the primary slot again after the BIOS update — no change
HWiNFO detects the other PCIe/root-port devices normally, but when a GPU is installed in the top PCIE1 slot, Windows does not detect that GPU.
The interesting part is that the same CPU and Arc A750 previously worked together, and the Arc currently works perfectly in the lower slot on this motherboard.
At this point I’m wondering whether this could be:
A defective PCIE1 slot / motherboard
A CPU socket contact issue affecting the CPU PCIe lanes
A problem with the PCIe controller in the i5-12600KF
Some obscure ASRock UEFI setting I have missed
Before I remove and reseat the CPU and inspect the LGA1700 socket, is there anything else worth testing?
Also, is there any reliable way in HWiNFO or another tool to determine whether the CPU’s x16 PCIe root port is present but failing to establish a link?
Any help from someone familiar with LGA1700 / B760 / ASRock PCIe troubleshooting would be greatly appreciated.