DC7800 Minitower Multiple GPUs

[Sarah152]

Hi there,

I have an old DC7800 Minitower that I'm trying to install two gpus into. The first one is a GTX 1080 which plugs straight into the PCIe x16 slot on the motherboard. When I start the desktop with this gpu the system runs perfectly and outputs to the display through this gpu without any errors. I then install a second card, GTX 1050 ti using a riser (PCIe x16 to x1) inserted into the PCIe x1 slot. When I start the computer with this gpu also installed I get the blue screen of death which just keeps rebooting. When I just have the GTX 1050 ti install into the PCIe x16 slot the computer runs fine and the drivers are recognised. It's only when I have them both plugged in the computer boots into the blue screen of death. Does anyone know a fix for this. I read somewhere that turning "4G decoding" on in the BIOS sometimes fixes issues like this, however this computer doesn't seem to to have this option in the BIOS? 

Any suggestions are welcomed, thanks!

[Prométhée]

Hello
Port 1x is probably insufficient, the adapter may not do everything!
moreover if your power supply is insufficient you cannot install 2 graphics cards as powerful
You would be better off installing a more powerful graphics card, than two totally different ones if your power supply allows it.

[Sarah152]

Thanks for your response. I forgot to mention that I have a separate 750w power supply powering the GTX1080 and powering riser which powers the GTX1050 ti. The new PSU is connected with a splitter so the HP power supply is still powering the motherboard but they both turn on the same time when starting the Desktop. I don’t think this would a the cause of issue due to to there being plenty of power from the new PSU but I could try connect the new PSU to the motherboard aswell