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What type of coolant in h100i


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I bought a 4year old h100i! I wonder

(1) whats in the system, is it distilled water or some other type of special coolant which doesnt transfer electricity?

I want to change the tubes and change the coolant, so i wonder

(2) should it be enough with distilled water or better some type of coolant from the shop or mixture of both!

(3) am i right that any of these special collants used in these type of cooling systems dont transfer electricity if spilled on the mobo, vga? and distilled water, hows with that?


Thank you & Best Regards,


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No, all coolant mixtures will still be conductive. If it doesn't conduct electricity, then it won't conduct heat either. Some coolant products are labeled as "low conductivity", but whether marketing lingo or not, you don't want this stuff on your motherboard or anything else.


Most AIO coolants are a mix of mostly water, Propylene Glycol, and then trace amounts of anti-corrosives and biocides.


This is a rather tricky endeavor you are contemplating. There is no refill valve, drain, or disconnects on the unit. You will have to forcefully disconnect the hoses and drain it. You will need to reattach your own after-market tubing, with a disconnect/drain/fill valves. Then add your own coolant (they sell pre-mixed stuff). Assuming you have done all this perfectly, you will still be powering the system with a 4 year old pump that could kick off any day. Obviously the warranty is void the moment you take out the utility knife and I am not sure what the benefits would be. You are not likely to see any meaningful performance gain, there is a definite measure of risk, and it does not address the two most important parts of the system (pump and radiator). The parts needed to do this will likely cost at least half as much as a new AIO cooling system, but will still be limited by the remaining life of the pump. If you are experiencing decreasing performance, a new AIO cooler would be more expensive (maybe), but at least the cost could amortized over the longer lifespan (hopefully) and comes with a 5 year warranty. If you are doing this as a science experiment, that's one thing, but if this cooler is a necessary part of your operation, I only see negatives in pursuing this path.

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This could be a science experiment, of course :) only one thing im worried is - not to spill anything on my mb and emu 1616m... i understand, that there is no such thing as non-conductive liquid! ..it is, but only if its in the system :)


Anyway, the guy i bought this h100i from, he used it in the system all the aprox 4years, he told me that everything was fine till he dismantled it, h100i was mounted only in one position all the time, i understood - over the cpu on the top of the pc case!

So i went home, put the hardware together and wolla, a flow problem! a big one! if i start my rig, aprox 3 minutes and the incomming liquid to the block gets past 50degrees easy and the xeons hottest core (max TDP 80W, stock 3Ghz - no oc at all) goes to about 80 (cpu usage aprox 10-20-30 / switching cores)! when i take the rad and shake it, 50% of the time nothing happens, 50% of the time i see very rapid decrease in temps, 1degree in aprox 2seconds.. it goes some max 10 degrees down and stops and starts to slowly, sometimes faster rise again! sometimes i fell that the outgoing tube temp isnt so hot at all even the cores are aprox 60-80!even then when incomming water readings are 50-55 and more! i usually dont have much time to experiment, need to shutdown system after 3-4-5minutes!yesterday i got few times stable idle at 45-55, but its rare, most of the time, temps go up fast!

I dont hear nothing in radiators, no air, definetly no air, no crackle, no loud sound, nothing, so the questions is - what the hell could it be!!! BUT.. if i gently knock on the block, 100% of the time the temp goes slowly down some 3degree before rising again, so i suppose the block occurs in the cooler block AND in the rad also! it coul be, that after the 4year usage in one position from moving it, the dirst or whatever get loose and now thats why i have this flow problem! i cant imagine an other cause!

thats why i asked about the h100i liquid inside, can it happen, that after 4years or more the liquid gets to some type of gel or leaves some rubish, dirt inside which get stuck in the rad and cooler block?

so i want to open and take a columbus look what the hell is going on, and if i open it, i will need to close it :) i dont have any other options!

dont have money for a new one!


So the questions is - if its not air, then what..?


the software is flaky too, pretty often it just freezes and doesnt show the actual readings, i must then exit the software and run it again... im not happy, i undersand, that its because the h100i a grandpa now after 4-5year usage and needs some antibiotics to last longer..its my first water cooling, i know now, never buy a used one because u dont know in what condition it is, u dont see through nothing! i read people often have the same problem with different manufacturers, it worked like a charm, then they move it, realign it and wolla temps to the sky!


and one more question - in closed system > how much air can it be there, the percentage!? because i understand if we open the h100i, clean it, change tubes, refill and close it, there will be air definetly!!! of course no air - GREAT, but in the real life i think in every system there is air a little or more!

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OK, then this is an experiment. No warranty to void since it is second hand and you do have an existing problem. Changing the coolant may partially address the issue, but I wonder if it isn't something a little more. One of the more common failings (relatively) in nay brand of AIO is elements of the sealant come off and become part of the water flow. It then collects at the pump strainer.


This is NOT a Corsair product, but does clearly depict a worst case scenario. I had one of these once upon a time.



You shake, it temporarily dislodges, but it will always find its way back to the drain. I might start looking there. The rest of the cited thread is here.

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omg, it looks ugly!

Ok, in the weekend we will try to solve the problem!


Can anybody tell how much / how little air in the system is allowed not to affect the temps so much? Or do you know what should i do to minimize the air left in the cooling system?


If i will seal the the closed system at home, there will be definetly some air inside after the process..

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  • 5 months later...

I use Corsair Hydro Series H100i CPU Cooler in my older gaming computer as I thought it was coolant refillable, but as I found out, that's not the case.

So I might have to purchase the Fractal Design Kelvin S36 Highly Expandable Liquid CPU Cooler as I have in my main gaming computer and that I changed the coolant just for some days ago to the new EKWB EK-CryoFuel Premixed Chemically Stable & Thermal Efficiency Clear Coolant.

This was the plan to do even with my Corsair Hydro Series H100i CPU Cooler as I thought was possible. But nothing wrong with a Corsair Hydro Series H100i CPU Cooler as a backup :sillygrin

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