Just to clarify skylers diagram.The amps that the TEC pulls at a given voltage is dependent on the delta across the TEC, the higher the delta, the lower the amps/power consumption, the lower the delta, the higher the amps/power consumption.
As the maximum delta is reached when there is no heat load applied to the cold side, we can put the minimum amperage the TEC will use at 12v at 0QcW, 6 amps. The maximum amps that the TEC will pull is at Qmax with 0*c dT, so for 12v that is 165w Qmax and 0*c dT, like this
from that, you can extrapolate dT, Qc and power consumption of the TEC.
One caveat though, because that TEC can't reach dT Max at 12v it would be a slightly different line than what I have drawn, the spec sheets are not accurate enough to make perfect estimations so real world results will differ.
To effectively cool a GPU with a heat load of 140w and have a decent delta, you usually need the Qmax of the TEC to be at least double the heat load, ie 280w Qmax TEC, but actually I would recommend a 400w Qmax TEC (ebay tec's advertise power consumption, not Qmax, their Qmax is much lower than their power consumption, Custom Thermo Electric (CTE) lists Qmax, so if you want to buy a TEC from ebay, compare the volts, amps, couple count and size of the ebay tec to the CTE tec and that will give you an approximate idea of how good the ebay TEC is, minus the lesser quality of ebay TEC's of course.)
to help with deciphering ebay TEC's couple count of a TEC directly relates to it's voltage, ie a TEC 12715 would be a 15v, 15amp TEC, the 127 is the couple count, 127 couples = 15v, the 15 is the amps. ebay is mostly 127xx TEC's, there are some 199xx TEC's on ebay though, these are 24v.
TEC's perform best when run at 50-70% of their max voltage, for this reason, if you are using a 12v ATX PSU to power the TEC, I would try to buy a 199xx TEC and avoid 127xx TEC's, the 199xx TEC's are much more efficient at 12v than 127xx TEC's
The CTE 400w Qmax TEC at 12v is perfect for chilling a 140w GPU, but it is a 62x62mm TEC, so you need special water blocks, you could try to use 2 of the 225w 40x40mm TEC's, but that means more water blocks.Edited by LiamG6 - 4/11/17 at 6:31am