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ASUS Z490 + Intel Pentium Gold G6405 + AMD cards not working



could anyone help to discuss the reasons why my rig doesn’t boot, please?
MB ASUS Prime Z490-P 6xPCIe + 2xm.2 (latest BIOS)
CPU Intel Pentium G6405
5x Sapphire Radeon Pulse+ RX6800XT
1x AMD RX6800
1x Sapphire Radeon Pulse+ RX5700XT
1x Sapphire Radeon Pulse+ RX5600XT
2x Corsair RM850

The problem. All cards are working fine BUT the rig doesn’t boot when there are more then 4 cards connected to the MB. It doesn’t matter which cards I connect. Any 4xcards combination is working.
Risers seem to be fine. All connectors are properly connected, risers are v009s so they are displaying when the connection is ok.
When I connect any 5th card (PCIe) the rig doesn’t boot. Everything seems fine (mb on, all leds on, cards’ lights on, fans spinning) but the display (connected to iGPU via HDMI) doesn’t turn on.
After I turn the machine on and disconnect the card it’s booting ok again.

I have another rig with same MB ASUS Z490-P, same CPU with 8x nvidia cards and that one is stable and running nicely all the time.

What might be a problem? What am I doing wrong?

Any help appreciated.
Thank you.

I got the same mb and connected 8 cards to it with 0 problems, now using 7 because no room for the 8 one. the only change I made was changing the pcie gen to version 1 instead of auto

I am pretty sure I tried that. But today I saw some more settings I can try like disable VT-d etc.
4G encoding is enabled, I disabled unused devices like HD audio, SATA (booting from flash drive), serial port.
Anyway, thanks for sharing, I know there is a way just need to find it.

I am using the sata with the ssd I have

I got it working yesterday by disabling VT-d and some more setting in BIOS setup.
Now running 2x5600XT, 6800, 6800XT. 2 cards via m.2 → PCIe adapters.
Still need to tweak the OC a bit, hoping for more effectivenes.

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Hey dude. Could you please tell us wich other default settings u changed in order to make it work with +4 GPUs?
I’m going crazy. I’ve tried a lot of different settings within 3 diff BIOS releases

thanks in advance

I built 3+ 8 card based rigs based on Asus Z490-P with Pentium G6405 in last 2 months.
I also boot from flash drive, recommend Samsung Fit 16+GB, it’s fast and small and pretty cheap
Just use the latest BIOS. Advanced mode (F7)
I don’t touch anything in Main and AiTweaker tabs (although some say to disable any OC helps)

In advanced tab Disable:
-Platform misc configuration
– PCI Express Native Power Management
– Native ASPM
– L1 Substates (disable or auto, I don’t remember)

  • CPU config
    – SGX disable
    – Intel VMX disable

  • System Agent
    – VT-d disable
    – Above 4G decoding Enable !!!
    – Memory remap Enable
    – Graphics - PRimary CPU
    – DVMT Pre-Allocated 128MB
    – PEG Port Config
    – PCIEx16_x both Auto or Gen1

  • PCH Config
    – PCI Express - Speed Auto or Gen1

  • PCH Storage
    – SATA Disable if you are booting from flashdrive

  • Thunderbolt DISABLE

  • SR-IOV Support disable

  • Network stack Disable (we’re not booting from network)

  • Onboard devices
    – Hyper M.2X16 Disabled
    – HD Audio Disabled
    – USB Power delivery Disabled
    – Connectivity mode Wifi+BT Disabled
    – LED lighting All On (give 100MH/s - just kidding :-D)
    – Serial port Disabled

  • APM
    – Restore AC Power Loss - Power On
    All other disabled


  • CSM Disable
  • Secure boot - Other OS

and many times loading optimized defaults and then re-setting the above settings helps. Especially after connecting the cards.

Good luck


I set up the asus prime z490p according to this manual and my 10 GPU mix nvidia / amd works

ASUS PRIME Z-490-A Motherboard BIOS Settings x6 GPU Help - #9 by An9elo_RZ ASUS PRIME Z-490-A Motherboard BIOS Settings x6 GPU Help - #9 by An9elo_RZ

1 Like

thanks man

thank u VM!