I've been working immersion for a while now too. I have the refrigeration unit already, I picked it up a week ago, and the computer components, but I have been stuck on what coolant to use.
What I have gathered is that most oils will degrade components, seals, and component caseings within a year or so. Which is fine if this is just an experiment or you don't mind replacing your system every now and then. They are pretty thick at the temps we are looking at anyway. I just got an email today telling me to forget alcohol too, which came as a dissapointment since that was what I thought I would probably end up using. Eugene has a pretty impressive resume in the area of chemistry and cryogenics. I looked at some of his research and it deals with pretty serious alcohol chemistry, so I am gonna trust him on this. I found him randomly
here. Knowing now that he started a cryogenics company and that he is in the ranks of the OC'ers, I will assume he has "expert witness" status and has considered all of this before I showed up, and regrettingly accept his advice. Thanks Eugene.
Moving on, DOT5 brake fluid is out too I think, it is pretty crude stuff. So, after getting rid of all the oils that I have found so far(mineral, transformer, machine....), alcohol, and brake fluid, that leaves on my list fluorinert. Maybe Syltherm, but I would need to contact Dow's techies about it before I pay that much or put my board in it. It is after all, just a silicone oil. I called 3M yesterday, but with it being good Friday, there were hardly any techs to talk to, so I only spoke to the operator. I ended up leaving a message for the most appropriate tech guy after getting a few too many voice mails. Hopefully he will call early next week. The operator put me in touch with my local rep for sales info too, but she was gone also. The op would not/could not give me pricing, and kept dodging the question.
Spring break is almost over, and so is my time. Eugene recommended trying to contact local recycling centers or the electronics industry for used Fluorinert. I will try to look into that next week, but the semester is going to start in full throttle. I just dismantled and "prepared" an old psu and container to use as a guinea pig in an immersion test. I am ordering a pelt to use as both the load and cooler, so when it gets here, I will need to have some fluid ready. I've got my fingers crossed, but I am gonna go get some drinks

and forget about this for a while. It is, after all, the last night of break for me

I need a camera too
As a P.S. There are several threads that deal with this, let's try to keep them together and just use one. I don't have time to keep searching for this stuff. Also,
this lifted my spirits a little. What are we doing? lol