Nah, watercooling laughs at 200W (a.k.a. Q6600 @ ~3.6Ghz). If you've got the necessary radiator footage elsewhere in the loop, you can dump all kinds of heat through a single waterblock. If you look at the Arctic Web water block, designed for a 437W peltier (plus the actual heat dump of the processor, of course), that's all being conducted through a measly 60x60mm of surface area. For the Swiftech block, yes it will be dealing with that kind of power at full rated voltage, so make sure the heat is dealt with, or the TEC will burn itself out.
Have you ever seen this thread? Might prove insightful. But yes, peltiers are easily reverseable. Just switch the +ve and -ve wires, and they'll try to move heat the other way. With the caveat that the peltier's heat still has to be handled somehow.
i7 2600K | ASUS Maximus IV GENE-Z | GTX Titan | Corsair DDR3-2133
Pelts , eh.... I'm not sure you wanna go there or not.
Here's the thing about peltiers :they are very inefficient.
My last peltier project used 3x 226w peltiers.This is a suitable dissapation for say a high end CPU /northbridge and 2 video cards.
Here's some stats about that.
Lets assume 75% heatload on the pelts. (500watts)
The 'hot' side of that peltier system needs to dissapate in excess of 1.1 Kw . It also requires a power supply capable of providing ~700 watts @100% duty cycle(12v ,60A)....
Your average run-of-the-mill watercooling system really isnt designed for that kind of heatload , so you'd be building a custom watercooling system for the 'hotside' cooling as well.
Peltiers do work tho , and they are quieter than an AC unit.If you get electricity for free , pelts would be a great way to go.....The cost would be a lot more for pelts however , considering you can get a 5000BTU AC for 100$.