Can you file the key off the top right pin of a PCIE cable to fit the female end of a PCIE cable extension mod?

[Horninn]

I recently had rma my Corsair rm750 after it died a few weeks ago. Since it was gonna take some time to get the replacement I decided to get a cable mod set to help with cable management. Sadly it appears that the Corsair PCIE plug has a key or nub on the top right connector preventing it from mating with the female end of the extension. Is it okay to file this off to make the connector flush? Just need to see if I need to get another set of PCIE extensions, the cpu and motherboard extensions appear to work perfectly fine.

Thank you