New GPU has led to black screen. Old GPU no longer outputs display either

Aug 15, 2018
I made some mistakes due to not reading up on this topic before starting out the switch of GPUs.

I have a HP Z600 running windows 10. I had an Nvidia Quadro FX 400 installed but went to switch out for Nvidia GTX 970. I didn't update drivers/bios anything before doing this.

Switched off swapped out, seated well and plugged the new card into the PSU. Computer started but was evidently using the onboard graphics as resolution was low and 75% of the screen. After maybe 1 or 2 minutes tops the display went black. Restarted (a few times, computer power button) no display at all.

Resorted to putting the old GPU back in. The same issue of starting in low res then black screen. Now I have black screen on both cards from start up.

I've read of mother board vga/hdmi slots to reset or update bios - I have double and triple checked, I don't have one.

The Quadro has a VGA and a display port - neither are outputting.

Same story for switching outputs on the GTX.

I have two 16x PCIe slots (75W if that makes a difference) and moving between slots makes no change

I've checked I've not knocked any other cables out of their seating on install

Thank you in advance for your help



Can you get to BIOS?

I would suggest that you power down and unplug from the wall socket. Remove either GPU's and remove the CMOS battery from the motherboard. Replace it after 15 minutes.

On another note, when upgrading a GPU, it's advised that you uninstall your current GPU drivers, remove the old GPU and after dropping in your new GPU, install the latest GPU drivers found off manufactures support site.