Upgrading PS extender card in t5810

Hello!

I’m pondering with putting a newer, more powerful GPU in my Dell Precision Tower 5810. I currently have the 685w PSU, but I’m thinking of upgrading to the 1300w PSU from the t7910 (v5k16) that’s compatible with this model as well. 

I, however, would still run into a problem powering the GPUs that require let’s say 2x8 pin connectors from two separate rails/connectors. The t5810’s power supply extender card only has one PCI connector input for GPUs. I can see that the t7910’ PCI card has more connector opportunities and therefore I’m wondering: would it be possible to upgrade the currently extender card with one that has more connection options?

First I thought upgrading the PSU and putting a 8pin to Dual 8 pin in the current extender card instead of the 8 pin to Dual 6 pin could help me, but it seems it wouldn’t be good to power a GPU requiring two 8 pins from the same connector.

I hope you can help me in gaining some more knowledge on the matter!