New build on B360 mobo will not boot on dedicated GPU, does boot on integrated GPU

[bestpolishelder]

New build with old gpu will boot no prob on integrated graphics, but will not boot with dedicated gpu plugged in.
Gigabyte B360 aorus gaming 3 wifi (BIOS F3 - latest)
i3-8100
GSkill DDR4 2400 8GB (2x4GB)
Nvidia GTX460
PSU 600 watts
500 GB M.2 SSD
I have tried multiple PCI slots, GPU works in another PC just fine, I have also tried a brand new EVGA GT 710 with same results, thinking it could have been a power issue for the 460. I've checked and rechecked the BIOS for any useful options, I have PCI slot 1 set to default and Integrated GPU set to auto, and I've tried several configurations of BIOS settings with no luck. The mobo has an LED for self test for CPU, RAM, VGA, BOOT and it goes through CPU, RAM quickly, then hangs on VGA. No video output, never gets to POST.

 

[weberdarren97]

Are you sure that you plugged the power from the PSU into the GPU?

 

[weberdarren97]

http://www.tomshardware.com/faq/id-1893016/post-system-boot-video-output-troubleshooting-checklist.html

 

[bestpolishelder]

Are you sure that you plugged the power from the PSU into the GPU?

Thanks for the response. Yes, both 6-pin connectors. The fan spins up fine, no indications that it isn't getting power. Also tried the 710 which doesn't require external power. Makes no difference.

 

[bestpolishelder]

http://www.tomshardware.com/faq/id-1893016/post-system-boot-video-output-troubleshooting-checklist.html

Excellent troubleshooting guide, everything on my build looks good according to this. Again, it boots fine on IGPU, just not on dedicated GPU. I can't find any help on the BIOS settings that would ensure proper recognition of the GPU.

 

[weberdarren97]

Are you sure that you plugged the power from the PSU into the GPU?

Thanks for the response. Yes, both 6-pin connectors. The fan spins up fine, no indications that it isn't getting power. Also tried the 710 which doesn't require external power. Makes no difference.

I recommend removing the GPU so that it boots, then going into BIOS and loading optimized defaults. Then try again.

Note that my Ryzen system got hung up at GPU detection the first few times I tried to turn it on, but then worked after a few tries of doing the exact same thing. Not sure why it suddenly worked... Maybe I got lucky?

 

[weberdarren97]

I just looked up your motherboard. Seems you have 2 different M.2 slots where you can put your SSD. Let's try the other M.2 connector, just in case the one you're using is stealing VGA bandwidth.

 

[bestpolishelder]

Are you sure that you plugged the power from the PSU into the GPU?

Thanks for the response. Yes, both 6-pin connectors. The fan spins up fine, no indications that it isn't getting power. Also tried the 710 which doesn't require external power. Makes no difference.

I recommend removing the GPU so that it boots, then going into BIOS and loading optimized defaults. Then try again.

Note that my Ryzen system got hung up at GPU detection the first few times I tried to turn it on, but then worked after a few tries of doing the exact same thing. Not sure why it suddenly worked... Maybe I got lucky?

I just looked up your motherboard. Seems you have 2 different M.2 slots where you can put your SSD. Let's try the other M.2 connector, just in case the one you're using is stealing VGA bandwidth.

Reset the BIOS back to defaults, no change. I'll try the secondary M.2 slot.

 

[bestpolishelder]

I just looked up your motherboard. Seems you have 2 different M.2 slots where you can put your SSD. Let's try the other M.2 connector, just in case the one you're using is stealing VGA bandwidth.

Well, that did it! Interesting. With the SSD in the 2nd M.2 slot and the dedicated GPU it boots fine. Thank you for your help, now I need to understand why, and if I can get it back into the 1st slot or just forget about it. Any reason I wouldn't just leave it in the 2nd slot?

 

[weberdarren97]

As for why it wasn't working, it's possible that the M.2 slot was using bandwidth that was necessary for the graphics card to properly communicate with your CPU. This is not uncommon with newer boards, since companies are trying to cram more and more connectors onto these boards, but the boards themselves are not getting bigger. What they do is make 2 connectors share bandwidth with each other.

Imagine a very short highway. There are 2 entrances that then squeeze down into one lane. I'm sure you can see how this would cause a traffic jam. Even though it splits into two exits at the end (PCIe and M.2 connectors), that doesn't change the fact that your graphics card and SSD were fighting to both use that single lane highway. Sometimes it works, sometimes we have to move the SSD. Not sure what it seems to work sometimes and not other times.

The difference is that the first slot is operating at PCIe 3.0 X4 speed and the second is operating at X2 speed.

That's a theoretical 1.85GB/s (roughly) vs about 3.5GB/s. Note that both of these speeds are plenty fast enough to keep your SSD fed at its maximum speeds. If not, it will be a very small and probably unnoticeable loss, as what you use your computer for probably doesn't max out your SSD anyway.

Things that would max out your SSD would include massive files being moved to/from another storage device that's at least as fast as the SSD, compressing or decompressing absolutely gigantic files/folders, etc.

I don't think you're really losing anything by keeping the SSD in the second slot.