Need pcie cable

I recently upgraded my gpu to a 7900xt, but i dont have enough pcie cables to power the 3 8 pin connectors. Is it safe to buy one pcie cable to use, and if so which cable do i need? I have a Corsair RM850e. I will link the psu below as well. Thanks!!

https://www.amazon.ca/Corsair-RM850e-Modular-Low-Noise-Supply/dp/B0BYQPH5J3?th=1