Hmm, you'd think so, but not quite.
Go to McDonald's and buy a soda. Stick a straw in it. Suck on the straw, you get soda in your mouth. Perfect.
Now put a hole in the straw above the soda. Suck on the straw and you get nothing but air, maybe a little dribble of soda.
That's a rear exhaust as a passive intake. That top/rear aio fan will be pulling fresh air directly from that vent. Yes your cpu temps will be a few °C lower, you've got a source of colder air very close to the fan, but the byproduct is less draw of case air from above the gpu. If you keep the aio fans higher rpm, that's going to minimize that affect, the gpu exhaust will be directed more towards the front aio fan, but overall after a longer gpu exhaust period, the affect on the gpu will be higher temps as the case air is more stagnant.
With GPU Boost boosting according to temps, you'll end up with a smaller boost, worse speeds and performance, same gpu temp reading.
It's the nzxt H510 affect from a different angle. Changing airflow patterns.