Windows 7: how hot does a mineral oil submerged computer get with a cooler?

I'm planning to build a miner oil submerged computer, but I need to resolve a few technical difficulties first. The major one is sealing holes.



Due to the nature of my build, all cables enter the tank from the bottom. Therefore, I have to find a way of sealing the hole that the cables pass through, while still allowing for the addition or removal of cables at a later date. The only way I could find to do this is to have something I can hand-mould to seal the gaps, which doesn't dissolve in Mineral oil, but can be easily removed without risking damage to the cables or me.

The solution I came up with is a thermoplastic that is mouldable at about 60-80 degrees celsius (any higher and I risk burns and damage, any lower and I'm at operating temperatures).

The problem is that I was reading online, and the only information I could find indicates that mineral oil computers reach 80 degrees celsius under load, at which the plastic seals would start melting.

I do plan on using coolers, but I can't find how much that affects the temperatures.

Any advice? How high do you find temperatures get with systems you know of?

Thanks.