If you're considering upgrading your gpu, you need a bigger psu, otherwise you're stuck with 1650 as the only possible and available upgrade.

I ran my gtx 970 off a 500W psu (before it had 530W). So I'd reckon you need around that much power for medium high gpu. But if you intend to get the brand spanking new 30 series, you'd probably need to aim higher.

After psu, you cab go for RAM - at least add another 8gb.

Then after this, you might want to add ssd storage so that your games load faster, maps/transitions load faster, etc.