PC fails to boot when known good pcieX4 usb C Riser card is installed

[theRatty]

Mobo x570 taichi

Gpu 3080 fe

Gpu in the top slot mounted vertically with a PCIe 4.0 cable

bottom PCIe X1 slot filled extension cable to back of case with riser card USB 3.0X2 internal connectors (one of those converted to 2X USB 2.0 headers)

When a PCIe 3.0 extension cable is connected to either of the other two X8 slots and connected to the known good card the PC will boot loop going through several postcodes with no output. I will note that the GPU fans run and power is being sent to the monitors upon startup as the backlight is visible but no display out.

 

Am I not supposed to be mixing pcie cable types? Am I demanding too much bandwidth from the motherboard? If the only unknown is the cable does that mean it is defective?

[ThousandBlade]

dive into bios and see if setting PICe3.0 on the PCIE slots manually help.
if that doesn't work.
Unplug GPU, run screen from integrated graphics. then plug in the 3.0 extension. see if that works.
you should be able to isolate the problem from there.

[theRatty]

8 hours ago, ThousandBlade said:

dive into bios and see if setting PICe3.0 on the PCIE slots manually help.
if that doesn't work.
Unplug GPU, run screen from integrated graphics. then plug in the 3.0 extension. see if that works.
you should be able to isolate the problem from there.

I'm not sure how to do that in the bios and I don't have integrated graphics. Should I just get a pcie 4.0 cable?

[ThousandBlade]

13 hours ago, phatrattyy said:

I'm not sure how to do that in the bios and I don't have integrated graphics. Should I just get a pcie 4.0 cable?

Getting a PCIe4 cable doesn't guarantee a fix. There's still a chance that the slot is busted.

 

Depends on how much your time is worth.

There's 2 ways of fixing a problem, finding out what the problem is, or throwing parts at it until it's fixed.

One cost time the other costs money.

You'll have to decide if you wanna spend the time figuring it out, or spend money on it and spend the time you save on making money.

[theRatty]

2 hours ago, ThousandBlade said:

Getting a PCIe4 cable doesn't guarantee a fix. There's still a chance that the slot is busted.

 

Depends on how much your time is worth.

There's 2 ways of fixing a problem, finding out what the problem is, or throwing parts at it until it's fixed.

One cost time the other costs money.

You'll have to decide if you wanna spend the time figuring it out, or spend money on it and spend the time you save on making money.

I tried the 3.0 cable in both slots to rule that out...

[ThousandBlade]

14 minutes ago, phatrattyy said:

I tried the 3.0 cable in both slots to rule that out...

OK, keep the GPU connected, go into the BIOS and look around. 
just looking won't break anything, just don't save when you exit the bios.
i know it might look scary, lots of words and abbreviation you don't understand, but all you need to do it to look for sth to do with PCIE and speed, 3.0 4.0.

[theRatty]

20 hours ago, ThousandBlade said:

OK, keep the GPU connected, go into the BIOS and look around. 
just looking won't break anything, just don't save when you exit the bios.
i know it might look scary, lots of words and abbreviation you don't understand, but all you need to do it to look for sth to do with PCIE and speed, 3.0 4.0.

Will my 3080 fe run slower on 3.0?

[theRatty]

20 hours ago, ThousandBlade said:

OK, keep the GPU connected, go into the BIOS and look around. 
just looking won't break anything, just don't save when you exit the bios.
i know it might look scary, lots of words and abbreviation you don't understand, but all you need to do it to look for sth to do with PCIE and speed, 3.0 4.0.

Holy shit i just did that. Found the option to change the top by 16 slot to 4X4 which I didn't even know you could do but I found the option for the X8 slots to change to gen three also it had the ability to change to gen one and two which is crazy. Changed the other X8 slots to gen 3 and the card is now working!!!!! thanks!!!!

[Bjoolz]

25 minutes ago, phatrattyy said:

Will my 3080 fe run slower on 3.0?

The 4090 was 1-4% slower on 3.0, so probably not. Unless you are doing other loads than gaming and those heavily rely on bandwidth.