Air circulation works in two ways...
When the air is colder than XXX it cools XXX if the air is warmer than XXX it warms XXX
If you go second loop... I would just put the rad in the bath TBH... if you place your I/O right like Kal suggested earlier you will get enough medium moving through the fins...
But I am just guessing...never done it myself.
TBH.. it seems like GPUs benefit less from cold than CPUs... at least from what I see on the bot... there are of course exceptions either way.. but ... I would say wait for winter Imean submerge now... but if its too much load for serious Ocing... wait for winter..... get some fan extension cables.. throw your GPU rad out the window
I kept a pretty decent 0c on my AMD setup with just a 480GTX sitting outside...(and 4 ultra kaze 3Ks pumping air through it
)
Unfortunately the VRMS were not getting cold enough so I was still limited.