Combine 3 rtx 3090 with 2080 ti to mine bitcoin

Hi,

I tried to have 2 rtx 3090 ( 1 rtx 3090 PCIe X16 an one 1 rtx 3090 PCIe 1X) and 1 rtx 2080 ti (connect to 1X PCIe) connect to Z370 Gaming plus Motherboard and Cuda was able to detect all the 3 GPUs, Now I have another rtx 3090 connect to 1X PCIe but my Cuda is not detecting the 2080 ti even though my windows device manager is detecting it. I tried everything I know (uninstall 3090 then reinstall 2080 ti) but still not detected, Please advise if I can do something to make it detected by Cuda 11.2 or any other versions

nvidia-smi result on my windows 10:

Fri Jan 29 22:37:49 2021
±----------------------------------------------------------------------------+
| NVIDIA-SMI 461.40 Driver Version: 461.40 CUDA Version: 11.2 |
|-------------------------------±---------------------±---------------------+
| GPU Name TCC/WDDM | Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|===============================+======================+======================|
| 0 GeForce RTX 3090 WDDM | 00000000:01:00.0 On | N/A |
| 30% 31C P8 36W / 350W | 599MiB / 24576MiB | 2% Default |
| | | N/A |
±------------------------------±---------------------±---------------------+
| 1 GeForce RTX 3090 WDDM | 00000000:03:00.0 Off | N/A |
| 0% 32C P8 9W / 350W | 228MiB / 24576MiB | 0% Default |
| | | N/A |
±------------------------------±---------------------±---------------------+
| 2 GeForce RTX 3090 WDDM | 00000000:06:00.0 Off | N/A |
| 0% 35C P8 11W / 350W | 228MiB / 24576MiB | 0% Default |
| | | N/A |
±------------------------------±---------------------±---------------------+

±----------------------------------------------------------------------------+
| Processes: |
| GPU GI CI PID Type Process name GPU Memory |
| ID ID Usage |
|=============================================================================|
| 0 N/A N/A 1380 C+G Insufficient Permissions N/A |
| 0 N/A N/A 2528 C+G …me\Application\chrome.exe N/A |
| 0 N/A N/A 6040 C+G C:\Windows\explorer.exe N/A |
| 0 N/A N/A 6656 C+G …artMenuExperienceHost.exe N/A |
| 0 N/A N/A 6956 C+G …5n1h2txyewy\SearchApp.exe N/A |
| 0 N/A N/A 7636 C+G …ekyb3d8bbwe\YourPhone.exe N/A |
| 0 N/A N/A 8416 C+G …perience\NVIDIA Share.exe N/A |
| 0 N/A N/A 8548 C+G …nputApp\TextInputHost.exe N/A |
| 0 N/A N/A 9456 C+G …b3d8bbwe\WinStore.App.exe N/A |
| 0 N/A N/A 9796 C+G …8wekyb3d8bbwe\Cortana.exe N/A |
| 0 N/A N/A 10820 C+G …lPanel\SystemSettings.exe N/A |
±----------------------------------------------------------------------------+