So I have a full size OptiPlex 7010:

i7-3770

16gb ddr3 

seta SSD …

I want to upgrade to a graphics card, a 1660 probably. Anyway with the measly 275 what PSU I'm pretty sure this isn't possible. Can I upgrade my PSU to a 500w one. Like from corsair or EVGA. I was worried that though it might have regular 4pin and 24pin connectors, the pinouts would be different. Is this so and if it is what are my options???