first of all...
dont sink more money into this.
TEC cooling was really popular about a decade ago but was quickly realized to be an inefficient way to subambient cool.
If you are not getting subambient temps with your TECs then you are REALLY inefficiently cooling.
Here is the thing.
A TEC works by adding say 200W of electricity into this device and removing 150W of heat. It does not move it far, just from one side of the TEC to the other. Now after adding all that power to the TEC you still have to cool it.
Historically, a TEC is mounted to a CPU, then a waterblock is mounted to the TEC.
the boreas uses muliple TECs instead ofa single unit for the following reasons.
1) if on TEC fails the others are not affected
2) using multiple units allows one to space out the heat shedding to make a air cooler more efficient than a single 130W load.
3) Smaller TECs tend to be more efficient than larger ones
4) and this is related to 1/2 & 3.. cooling the hot side of the TEC more efficiently leads to better efficiency on the cold side.
5) smaller tecs used to be WAY cheaper than large ones so it was cheaper to run multiple smalls than a single large.
the problem you are having is temp swings. so what you need is a large mass to help maintain temperature levels (just like a LN2 pot or something) So try a copper clug or an alum one.
Realistic Ideas I can think of in your situation. (Honestly I would straight water cool, because hte increased electric cost for running the TECs and NOT getting subambient cooling is not worth it)
a) single high wattage TEC on a large copper slug mounted directly to CPU. Hot side goes to a waterblock and a single quad rad is capable of shedeing 5-600W of heat IIRc.. the lower the laod the more effective, like anything except electricity...
b) build yourself a watercooled boreas. the idea is basically you are removing that giant air cooled part and replacing it with a waterloop. Since I doubt all 4 of those tecs fit on a single waterblock you will probably be left with some kind of aluminum or copper block mounting. to get everything connected.
c) screw it, fuck ivy bridge, go back to SB and get yourself a nice waterblock and run single digit deltas with a single quad rad