Your pushing it
80+ power supply is only guaranteed to give you 80% that's 600w.
This is a common misconception - the 80% rating is an efficiency measurement only.
If you have a power supply rated for 750W, it should deliver
The rating means it will supply that 750W with 80% efficiency. This does not
mean it can only deliver 600W to your PC. This means it will be pulling up to 940W at the wall
80% of 940W is ~750W delivered.
At 100% efficiency, 750W at the wall would be 750W delivered.
At 60% efficiency, 1200W !!
at the wall would deliver 750W.
With an 80+ Gold (87% minimum), ~860W at the wall would deliver 750W.
These numbers are all absolute minimums, real world efficiencies will trend higher usually.
All of that said, it's better to err on your side of the equation. Loading a 750W PSU with only 600W means you won't blow the PSU or burn your house down