project freezer

[roadrunner999]

hey i wanted sum advice on a project that im working on.Taking a peltier unit 90w 40x40x3.6 mm and sticking it between the copper cold plate base of the h100 and the cpu.wanted to try this on a amd fx 8120 and overclock to 4.0ghz or evn 4.2ghz.Im hoping to get reading below 20 degrees celcius if possible.I saw sum pics where the peltier was super glued to the copper base in an cpu air cooler.Any advice in which i can go along with my project

 

[ssjwizard]

If you put a 90W pelt ontop of your cpu you WILL COOK IT. You absolutely can not use a pelt with a smaller rating than the heat source you have to cool. Matching that rating exactly even nets a 0* delta T and while it wont create a runaway temperature its going to make your temp worse by running the cooler hotter. To cool an 8120 you need a minimum of 300w pelt and that likely wont get you more than 1-2c improvement over the H100 by itself. If you really want to pelt it you WILL need something rated at 400w or multiple pelts. Pelts at this rating ARE 62x62mm. Will a H100 handle 400w of heat from the pelt + ~220w from an overclocked FX? It will but I have no idea what the delta of that coolant is going to be. You would probably need a decent custom loop to reap any benefits from pelt cooling worth attempting.

 

[roadrunner999]

i have a friend who took the ultra chill tec cpu cooler disconnected the temp sensor and upgraded the pelter to a 90w which he bought from amazon and molex it to the psu and over clock his amd 1090t to 4ghz and runs at 20 degrees celcius no condenstation.
What u thk abt that?

 

[ssjwizard]

He has never put that chip under load for an extended period of time. It might idle at that temp but once you kick up the wattage the pelt is going to fail to dissipate all the head and become a rolling fireball.

90w cooling device CAN NOT remove 125W of heat. Peltiers are rated by the maximum amount of heat that it can transfer from its cold side to its hot side with a 0 degree delta. An overclocked 8120 can break 200+ watts without trying. Cooling a 200w heatload by removing 90w of it leaves 110w behind which will add up by increasing the temperature of the coldplate/IHS until it reaches a point of failure.

The laws of physics do not change just because were overclockers.

 

[roadrunner999]

well hes a gamer freak and constant bu tru i nvr thk abt it if he has it underload.so if i had to stay wid the plane h100 on the 8120 wud it be a nice pic of i wnt it to be 4ghz

 

[Bobnova]

There's some conduction of heat between plates, beyond what is actively pumped.
Given the price of a pelt there isn't really any reason not to try it out, who knows it might work!

Things to be aware of:
If you get sub-ambient you may have to deal with condensation.
If you get sub-zero(c) it will form ice, if it goes over zero(c) that ice will melt into water. This is a major problem, as water shortens the life of electrical parts substantially.

IMO all forms of subambient cooling are best left for playing around with and benching, rather than 24/7 use.

 

[ssjwizard]

I wasnt trying to say that running a pelt cant work only that he needs to aim for a much larger device. If you have a PSU big enough to run a 400wthermal(550w electrical)@24v it could be worth going after.

The efficiency is awful on pelts but I still really like them. I am still considering one for my cube build personally though the power draw is my primary concern with the idea.

Well GL whatever you choose to do.

 

[Bobnova]

I totally agree with you in theory, but there are an awful lot of people who have used waterblocks with pelts that aren't >200w on OC'd high wattage CPUs without the CPU frying.
It's one of those reality vs theory issues where they don't line up well, heh.

No way you're getting well below zero full sustained load out of that small of a pelt on BD, but at partial load who knows.

 

[roadrunner999]

but wudnt the heat of the processor at overclock temps prevent condensation?

 

[ssjwizard]

If the CPU is idling at very low power the pelt can pull more heat than is being produced the temps will drop until it reaches the limit of the cooling to lower the hot side temp. Potentially going sub zero, but quite likely sub ambient. Its literally impossible to say exactly what will go on with your system as there are literally hundreds if not thousands of variables at play constantly.

 

[roadrunner999]

well i guess that is ther purpose of the temp sensor

 

[hokiealumnus]

You already have a CPU that draws a substantial amount of power. Do you really want to add a pelt to it?

As has been stated, you will need a significant sized pelt to do much with that thing under load. Those CPUs run hot. Very hot for AMD. I was running a full pot of LN2 that weighs approx 6lbs (read: hard to move!) and it ticked up three degrees when running WPrime1024M at ~6.4GHz.

Also mentioned was that, at idle, you'll get much lower temps. If it's sub-ambient you will have condensation problems and sub-zero, ice problems. The heat of the CPU at overclocked speeds won't do anything to prevent condensation if the setup gets below ambient temps. Unless you fold, the CPU will spend most of its life at idle and temps could potentially get that low, putting your components in a world of hurt.

Long story short, Bobnova speaks the truth -

IMO all forms of subambient cooling are best left for playing around with and benching, rather than 24/7 use.