Question Having trouble bypassing 1st GPU to the 2nd better one when restarting the PC.

[Srdjankovic]

Hi guys!
Hoping someone can help me with an issue I am having.
I've recenlty upgraded from a 1070 to a 3090 GPU, and since I do Octane rendering, I would like to have an ability to use both GPUs simultaneously, no SLI or anything like that.
The issue is that when I boot up the pc, it automatically makes the 1070 the main graphics card, in that when I plug in the Display port to the 3090, nothing happens, and the screen has no signal.
So once the pc boots up on the 1070, I am then able, with no problems, to just switch the DP to the 3090.
This seems like an ok solution, but every time I boot back up, it just reverts to the 1070, so I have to keep switching the port.
Tried setting things in my BIOS for what the primary and secondargy GPU is, but have no option like that.....its an old MSI x370 Pro Carbon MB with no integrated graphics.

Any help regarding this issue would be appreciated!
I would also like to note that both cards work in Octane, so there are no connectivity or power issues.

 

[Rokinamerica]

Have you tried swapping the cards positions?

I have no experience with multiple cards, but my thinking is maybe it defaults to the top GPU.

 

[Srdjankovic]

Have you tried swapping the cards positions?

I have no experience with multiple cards, but my thinking is maybe it defaults to the top GPU.

Unfortunately, since 3090 is huge, the setup only fits if its on the second slot.

 

[DRagor]

Have you first checked out if 3090 alone (no 1070 installed) can properly boot with DP cable?

 

[Srdjankovic]

Have you first checked out if 3090 alone (no 1070 installed) can properly boot with DP cable?

Hi!
Yes, that was my initial setup, then I decided to move it down and add the old 1070 on top.
So 3090 along with DP cable works without issues.

 

[DRagor]

Hi!
Yes, that was my initial setup, then I decided to move it down and add the old 1070 on top.
So 3090 along with DP cable works without issues.

Then most likely problem lies in card order on motherboard. 3090 should be on top. If you have insufficient space then consider using a riser.

 

[zx128k]

BIOS should be able to select GPU but once you hit Windows you can change primary and secondary monitor.

 

[Srdjankovic]

BIOS should be able to select GPU but once you hit Windows you can change primary and secondary monitor.

Yes, that was my thoughts exactly, but the msi bios doesn't seem to have an option for selecting gpus

 

[Deleted member 2947362]

Yes, that was my thoughts exactly, but the msi bios doesn't seem to have an option for selecting gpus

Is the PCIe slot you have the 3090 in only running at PCIe 3.0 x8 ? with the top 1070 running at PCIe 3.0 x16, doesn't PCIe 3.0 x8 restrict performance of the 3090 ?

 

[zx128k]

Is the PCIe slot you have the 3090 in only running at PCIe 3.0 x8 ? with the top 1070 running at PCIe 3.0 x16, doesn't PCIe 3.0 x8 restrict performance of the 3090 ?

I would expect both GPUs are x8.

 

[Deleted member 2947362]

I would expect both GPUs are x8.

wow they really have cut down with x16 lanes on these newer boards I know the cpu has It's own x16 PCIe and thought the motherboard chipset had x8 which seems really well tight of them to the least I don't want to say back in my day.

But back in my day motherboards even the mid tier had more lanes I'm sure of it I even had a system with quad fire HD3870 or might have been the HD3850's and with all four cards they where at x8 or 2 cards both x16.

Just seems a rip off with what we get these days.

 

[zx128k]

wow they really have cut down with x16 lanes on these newer boards I know the cpu has It's own x16 PCIe and thought the motherboard chipset had x8 which seems really well tight of them to the least I don't want to say back in my day.

But back in my day motherboards even the mid tier had more lanes I'm sure of it I even had a system with quad fire HD3870 or might have been the HD3850's and with all four cards they where at x8 or 2 cards both x16.

Just seems a rip off with what we get these days.

If I install a nvme drive in the right slot I lose x16 on the gpu.

 

[Deleted member 2947362]

If I install a nvme drive in the right slot I lose x16 on the gpu.

For how much these boards can cost .... They really are milking it these days, you could argue PCIe 4 has higher bandwidth but if they don't give you enough lanes then pfff, and in this case we are talking PCIe 3.0 how long has the tech been around now.

It's a bloody joke or crime I'm not quite sure which lol

 

[Deleted member 2947362]

The top PCIe slot is GPU_0 which is standard boot PCIe for grahic's cards

Making sure you computer is unplugged from mains electric you could try removing the 1070 from the PC leaving the 3090 in slot 2
Reboot the PC and go in the Bios, look for where you can select PCIe boot devices like where you can select boot from IGP if your GPU has built in GPU or PCIe
See if any other options may have appeared since removing the 1070, it might offer boot PCIe 2 ?

Then again it might not, it might just have Boot IGP or PCIE
exit Bios and allow the PC to load windows

After windows has fully loaded if it needs to reboot let it do it's thing, then leave windows and shut down the PC disconnect the PC from Mains Electric and replace the 1070
Do not plug a display cable in the 1070 only having the 3090 connected to your display

power up your PC let it boot to windows

I don't know if any of that will help but any software that can make use of the 1070s GPU does not mean the 1070 has to have a display connected to it

when you first turn on the PC it might still have the black screen until windows has loaded and uses the 3090 as default display when windows is running.
However the 1070 will always be GPU_0 and the 3090 will always be GPU_1 due to the PCIe slot they are plugged in to, as far as I know.
so you might have to just put up with black screen until windows has loaded it will not harm the PC in any way your just not seeing the boot screen's that's all.

 

[Srdjankovic]

Is the PCIe slot you have the 3090 in only running at PCIe 3.0 x8 ? with the top 1070 running at PCIe 3.0 x16, doesn't PCIe 3.0 x8 restrict performance of the 3090 ?

Omg, thank you for bringing this up. I checked my MB manual and indeed the top slot is x16 and the bottom one is x8. Did a couple of test renders and although it says the GPU is working at 100%, it still renders slower.
I think I will check one of the solutions from below just to see if it works, and then I will revert to the single 3090 setup nevertheless....the CUDA count thats being added by the 1070 is insignificant for such a headache.
Thanks!

 

[Deleted member 2947362]

Omg, thank you for bringing this up. I checked my MB manual and indeed the top slot is x16 and the bottom one is x8. Did a couple of test renders and although it says the GPU is working at 100%, it still renders slower.
I think I will check one of the solutions from below just to see if it works, and then I will revert to the single 3090 setup nevertheless....the CUDA count thats being added by the 1070 is insignificant for such a headache.
Thanks!

You are welcome and I am glad some of the information was useful to you.