I didn't notice any difference with voltages either.
 
I ended up putting a second 92mm fan on the left side by just zip-tying it to the slot bracket and nzxt bracket. It sits perfectly and I feel a lot of air flowing over all the chips on the left and top side. I noticed the temps dropped off a good amount too. I raised the memory to +750 and its staying under 70c with the door closed. While the door was off I was reading 66c on the chips and 70c off the back of the pcb. I was actually surprised that the temps raised when I put the door on. I've got a giant 200mm blowing down onto the card. The only thing I could think of is the aio hoses are blowing hot air onto the card from the fan but they didn't seem that warm to the touch. In any event I ordered some copper 14mm*4mm heat sinks for the memory. I'll report back once I test them out and I'll see if i can get a reading off the bottom memory at that time.
 
The fan is a ARCTIC F9 PWM PST - 92 mm PWM PST Case Fan. I've become a fan(no pun intended) for their fans. They're so quiet!
 
If I were to do this again, I'd probably skip on the heatsinks and just buy the arctic f9 fan and call it a day.  But I guess it all depends on how high your card can oc. The extra fan seems to add a lot of extra cooling for the little amount it costed.
 

yes, I zip-tied the Arctic fan to the pci-e case bracket since it takes up two slots still, there's plenty of areas on it to do so, and another zip-tie on the nzxt backet. seemed like the easiest solution without going crazy

sisblub
Do you need a fan on that side? What components need to be cooled on that side? Sorry I'm new to pcmr

That usually doesn't do much unless it was done by design for the VRAM that can get a bit toasty on these RTX series. 

The AIO brackets already come with a fan in the more important spot where the power section of the board is aka VRM.  Other than that, your AIO would be cooling your GPU.