MOSFET, south bridge, and northbridge

Planning on going sub ambient with my cooling so I will have to insulate everything. Is there any real benefit to cooling these components?
John

What will you be using for sub-ambient cooling? LN2/Dice/Phase change?

Overall there is no real point to cooling either of those. The mosfets will get cooled just by being close to the source (assuming dice/ln2) and will melt whatever is put on it (a fan will do fine to blow across)

Chilled water I believe from one of his other threads on this endeavor. IIRC, this is for daily driving.

Mosfets - no
SB - no
NB - only for certain benchmarks, otherwise no

To be perfectly honest, sub ambient on a daily driver is a waste. Stick to ambient water, and chill when/if you bench.

Ambient in my home is usually 76F (25C) and South Carolina is pretty humid. I only plan on cooling down to 60F (15C). I may go cooler just because I'm a tinkerer. The idea is to get rid of the noise of the 8 fans in the system by putting an A/C unit in the attic and remove the computer heat up there. If I can drop voltage and gain or maintain my current clock speed I'll be pleased.
John

Or...

Drop your daily driver overclocking to something a bit more appropriate for your noise goals...

Or....

Go Intel and use less than half the wattage of your current cpu.

Or...

Replace your space heater gpus with 2 nvidia cards (970/980) that also use nearly half the power.

You are going to use a ton more power in the AC and have what is, to me, a logistical nightmare to make this happen.



That said, I want to see pictures of this process, lol!

Thick8 said:

Ambient in my home is usually 76F (25C) and South Carolina is pretty humid. I only plan on cooling down to 60F (15C). I may go cooler just because I'm a tinkerer. The idea is to get rid of the noise of the 8 fans in the system by putting an A/C unit in the attic and remove the computer heat up there. If I can drop voltage and gain or maintain my current clock speed I'll be pleased.
John

Click to expand...

Pretty Humid and Sub ambient for a daily driver is going to be tough to do. When benching especially with only cold water, the condensation can get pretty bad. When I bench with cold water I always do a tear down after I'm done and let the board dry for a few days before starting it back up. Even with insulation if some water gets under or around it, you may have some big issues. Do you really need to be running 5.0 daily?

I like overclocking. Started when I installed the math coprocessor in my first rig.

AMD all the way. If it weren't for guys like me we all would be paying $1000 for a 2Ghz 2 core processor.

It shouldn't be that expensive ( I know that's a relative term) and logistical nightmares are just puzzles waiting to be solved.

I'll start taking pics when the GPU blocks and second radiator get here. I've never done a build log so this should be fun.

I was thinking cost of AC unit mostly plus the power to run it with the pc. The pump system I am imagining a pond pump may be needed to send it through such long distances with adequete flow rates?

I'm curious the runs you need with tubing? You thinking wall fish it up to the attic? How long is the run? I assumed the attic is finished and getting central air already?

Sorry for the 20 questions, this intrigues the heck out of me.

Edit: sorry, im a bit off topic...ill,look for your build thread.

EarthDog said:

I was thinking cost of AC unit mostly plus the power to run it with the pc. The pump system I am imagining a pond pump may be needed to send it through such long distances with adequete flow rates?

I'm curious the runs you need with tubing? You thinking wall fish it up to the attic? How long is the run? I assumed the attic is finished and getting central air already?

Sorry for the 20 questions, this intrigues the heck out of me.

Edit: sorry, im a bit off topic...ill,look for your build thread.

Click to expand...

I don't think it's OT at all. It's totally relevant. Plus....I'd like to know more too.
I'd also like to know if the OP has ever done anything sub ambient before?
I'm thinking probably not.

I already had the A/C unit. It's been sitting out in the shed for a couple of years. There will be no head pressure issues from the long run only added static pressure. I plan on using strait fittings and rigid tubing so as to minimize that. I'm going to insulate and run the pipes in the corner of the room and just drill through the ceiling.
The attic is not finished but it is insulated with a ridge vent. The A/C evaporator and computer radiators will be housed in an ice chest so there will be minimal heat gain in the recirculating coolant bath. I have a couple of Arduino boards (50% when Radioshack closed up) to control the A/C operation and maintain a regulated bath temperature. That way I can change the temp on the fly. I could even regulate coolant temperature based on ambient humidity but that's getting a little deeper into it thant I want right now. I will have to Plasticote and insulate everything that will be below the condensation point. I'll used closed foam and dielectric grease for that. The A/C unit is a 5000 BTU unit but I'll only be dumping about 3500 BTU's into it under full load so I'm not sure what my lowest achievable temp will be; but knowing me I'm going to find out

Mandrake4565 said:

Pretty Humid and Sub ambient for a daily driver is going to be tough to do. When benching especially with only cold water, the condensation can get pretty bad. When I bench with cold water I always do a tear down after I'm done and let the board dry for a few days before starting it back up. Even with insulation if some water gets under or around it, you may have some big issues. Do you really need to be running 5.0 daily?

Click to expand...

I have been kicking around the idea of using a closed loop chilled water system and then submerging the computer in mineral oil. Mat from Puget Systems said the oil becomes too viscous at about 10c but I wouldn't be using the oil to cool; only eliminate condensation.

The longer you run it, the cooler the oil will get. You would have to insulate the tubing, the block, etc in order for that to work (basically the same effort as the flip side, but much more potential for a mess).

My concern is using an unfinished and likely hot as all get out attic. I would have concerns with a window AC unit sitting up there sucking down 100F+ hot air personally.

Putting the A/C unit in the attic is just like hanging it out the window. The condenser has to be in a hot environment for the A/C to function properly. My biggest concern will be that it may be too cold in the attic in the winter to obtain proper pressure/temperature differential.
Mineral oil is non-hygroscopic so there will be no condensation worries with the components that are submerged in it. It is also Dielectric so there will be no worries of electron migration nor galvanic corrosion. Of course any components or tubing that is exposed to the atmosphere will have to be insulated. I've often wondered why people don't use an oil bath instead of going to all the trouble to insulate the MB when using LN2.
My thinking is that the components in the oil that are not waterblocked (ie. MB, PSU, SSD, etc) will receive enough cooling from the waterblocks just being in the oil. If not then I could add a radiator to the chilled water loop an place it in the oil.

Because most people like to sell their old wares. Soaking it in a bath of mineral oil certainly prevents that due to how hard it is to get off without damaging the board. And with artust eraser, you just pulle it all off, done. Not to mention, I wonder just how viscous(thick) it gets at such cold temps. I mean the guy said you will see it thicken at 10C... Can you imagine -170C+??

When I had a window AC unit, it worked fine in my 70F apartment. It doesn't need to be 'hot' to work properly. They are not made for being in an attic with such high input temps. You did mention though that you were going to use the arudinos to override the shutoffs/temp control on the AC unit, correct?

I'm an avid reseller of my old "stuff". It is how I fund my new stuff. It will take a couple of cans of electrical component cleaner to be sure. I'm going to dip an old video card in mineral oil tonight to see how hard it is to remove. And more importantly; will it still work.

I'm not going all that cold. In fact I'll be happy if I can get down to 0c with a 5000 BTU unit. I have a 12000 BTU unit at school but I use that to teach my students some principles of thermal dynamics.

A window unit has the condenser exposed to the outside. That's why it is in the window. Closed loop Phase change requires both a pressure and temperature differential.

Report back on its efficacy.

The cold comment was in response to why people don't use it with LN2 not for your application. Mineral oil's freezing temp is around -30C or so IIRC... so, it would just freeze around the pot.

I understand how close loop phase change works . Perhaps not how a window AC unit works though! The units I have seen take air in from the front (inside the house) and release cool air at the front top (also inside the house). The portion that goes outside is for the warm air that goes across the condensors. I guess its more difficult to cool 100F air in an attic than it is to cool 76F room which all goes back to the sizing of the unit, the energy needed to run it (ends justify the means? Doesn't have to but).

See pic below...(apologies for my lack of understanding here)

Just out of curiosity have you thought of doing a geothermal loop and forgo the whole A/C in the attic.

Mandrake4565 said:

Just out of curiosity have you thought of doing a geothermal loop and forgo the whole A/C in the attic.

Click to expand...

I thought of doing a geo-loop for my home A/C a few years ago when I dug a well for my lawn irrigation system. I need to recheck what the water temperature coming out of the ground is but I think it was about 60F. I hand dug the 40 ft well with some PVC pipe and a garden hose. supplies 12.5 gpm with the 1 hp pump I have. That would save the cost of running an A/C unit. Initial cost would be minimal as well; seeing as I still have the fittings and such that I used to dig the water well. I could make a copper manifold assembly that would go to a depth of 20 ft (I hit water at 15 ft) attached to insulated PEX tubing to get it into the room. HMMM... Only took about 2 hours to dig the original well. Could dig it right outside the bedroom and run the hoses through the crawlspace vent and up through the floor. Have to get under the house for the yearly inspection anyway. I'm going to go check the water temperature right now. BRB

I couldn't remember if the water temperature coming out of the ground was 58F or 68F. It's 68F (20C). Of course I had to use my pool thermometer as my digital one is at school. I'll have to remember to bring it home tomorrow. If I go with my original intention of just making the room quite then it would work fine. My concern is that dumping 3500 BTU's in a relatively small area may cause a rise in local ground temperature around the manifold. If that is the case then I may be worse off than I am now. May be worth the effort though. I guess I could always bore another hole if necessary or go deeper with the first hole and make a longer manifold.
I would probably sell off my current radiator and Apogee Drive II to offset the cost to build a copper manifold. Need to go do some research.
I'll be back.