Looks like I have to repeat myself, having both the hot and cold side of a Peltier in a single loop
does not work, it just adds heat to the loop. Single loops do not have a hot and cold part, it just equalizes. You need a hot & cold loop with the peltiers in-between.
This has been tried in the past, if you want to learn more about TEC's I suggest going some more OC focused forums.
The only way to add a TEC cooling to a single loop is by applying a big powerful TEC directly to the CPU(and/or GPU).
Edit: for clarification, this is the only working (non-direct) TEC setup I've seen:
Just a rough sketch, this obviously isn't a complete setup.