Alright so my P2 850 is doing something I've never seen before... I have a asus 3080 strix and I'm using extension cables to power it and make it look niiice right? Well my build has been acting a little weird so I wanted to do some tests without the extension cables. I plugged all the stock PCI-e cables back into my 3080 and after that my monitors just stopped working. I did a full reformate and checked all the cables 10x.... its acting like my GPU isn't even connected, but if I go back to the SAME EXACT cables only with extension cables attached my monitors work again and the GPU shows up again in device manager.... I'm so lost can anyone tell me what's going on?

Try using different displayport or HDMI cables as well. I know it sounds like it won't matter but try it. I've seen stranger things and it worked. 

zeisj
Alright so my P2 850 is doing something I've never seen before... I have a asus 3080 strix and I'm using extension cables to power it and make it look niiice right? Well my build has been acting a little weird so I wanted to do some tests without the extension cables. I plugged all the stock PCI-e cables back into my 3080 and after that my monitors just stopped working. I did a full reformate and checked all the cables 10x.... its acting like my GPU isn't even connected, but if I go back to the SAME EXACT cables only with extension cables attached my monitors work again and the GPU shows up again in device manager.... I'm so lost can anyone tell me what's going on?

You've got a faulty stock PCIe cable that makes a connection when used with an extension but not when plugged in direct.  Extensions probably have thicker more robust pins and sockets.
 
 

kevinc313
 
Sounds like bad connections at the PCIe power connectors/contacts between the stock cables and the card.  Do you have some fresh cables to try?  It's going to be hard to check the resistance of each connection without disassembling the card.

 
 
It would be trivial to measure the resistance of the cable while disconnected from the GPU and the PSU. Why would you need to disassemble the GPU?
 
 
 

Don't necessarily need resistance I would think, just continuity

If you have a multimeter, you can check the integrity of each line.

You learn alot reading on the different posts

jb355
keep reinserting the cables, the connectors should scratch eachother and make a better connection

I just watched a Linus Tech Tips video where he suggested the exact same thing.

zeisj
Alright so my P2 850 is doing something I've never seen before... I have a asus 3080 strix and I'm using extension cables to power it and make it look niiice right? Well my build has been acting a little weird so I wanted to do some tests without the extension cables. I plugged all the stock PCI-e cables back into my 3080 and after that my monitors just stopped working. I did a full reformate and checked all the cables 10x.... its acting like my GPU isn't even connected, but if I go back to the SAME EXACT cables only with extension cables attached my monitors work again and the GPU shows up again in device manager.... I'm so lost can anyone tell me what's going on?

Did you try using a different set of cables aside from those? Sounds like it has to be the cables, no?

thanks for the suggestions

It's hard to control the quality of the aftermarket cables. I rarely used them and only use original cables coming with the PSU if original cables are available.

This worries me about planning my 3080 Ti ITX build.

HeavyHemi

zeisj
Alright so my P2 850 is doing something I've never seen before... I have a asus 3080 strix and I'm using extension cables to power it and make it look niiice right? Well my build has been acting a little weird so I wanted to do some tests without the extension cables. I plugged all the stock PCI-e cables back into my 3080 and after that my monitors just stopped working. I did a full reformate and checked all the cables 10x.... its acting like my GPU isn't even connected, but if I go back to the SAME EXACT cables only with extension cables attached my monitors work again and the GPU shows up again in device manager.... I'm so lost can anyone tell me what's going on?

You've got a faulty stock PCIe cable that makes a connection when used with an extension but not when plugged in direct.  Extensions probably have thicker more robust pins and sockets.
 

Looking at the connector on the GPU I think that the following happened at some point: extension cable end which connects to the PSU stock cable has thicker non-standard pins which damaged the stock sockets on the stock cable by spreading them too wide to the point of no return, so when connected directly to the GPU these sockets don't make a good contact as the pins on the GPU are thinner.
 
This is a very awkward case anyway, but possible. In any case I would replace the cables with new ones before using them without an extension cable as bad contact can unfortunately lead to sparking / excessive heating with high currents. 8pin cable 150W / 12V / 4 pins => ~3A per pin if all are connected & working fine. Not extreme, but could create problems if some of them don't have good or just have poor contact.

Maybe this sounds dumb, but . . . did you use the correct connection on the modular cables?