Low cost sub-ambient benching solution?

[mackerel]

I know I wont be the first but I'm wondering, how much would dumping a ton of ice into a water cooling loop really help with OC and benching? My thinking is, instead of near ambient coolant temperatures, as long as there is solid ice in the res (assuming adequate mixing) the water will also be near enough to 0C. The question then is, how long would how much ice last?

Assumption: freezers in the UK for long term food storage are typically rated at -18C, so I'll take that as the effective ice temperature. To raise that to 0C would take about 10Wh/kg. Once at 0C to convert ice to water would take a further 92Wh/kg. This isn't bad... let's round it and say you get 100Wh/kg, at a 300W load you could get 20 minutes before 1kg of ice is gone. If you use a large bucket as makeshift reservoir, you could put several kg of ice in there and get over an hour and not have to worry about it.

The other question remains, how much benefit would this give? Essentially it would give around 25C advantage over ambient (depending on weather and if you run aircon). I was debating a WC loop for one system and this could be attempted before I fix it in place. Kinda hoping condensation isn't going to be a problem in the short term if I invert the mobo so any drips will not fall on it.

 

[knoober]

Ive heard of folks dropping their res or another part of the loop in/through a 5 gallon bucket of icewater before. Seems likely to be easier to set up and cleanup depending on your loop?

 

[mackerel]

I was thinking of trying this on a new loop I haven't even bought any parts for yet, so it'll be easy to do as a one-off. My existing loop... isn't easy to do anything with.

 

[Woomack]

Water will get hot quick. If you use radiators with ice or cold water then they will heat up water and melt ice faster. I've noticed that a bit of water like 200ml + large brick of ice in the bucket works the best for longer and it's melting much slower than small ice cubes. I wasn't using that for longer but it has better thermal capacity than a single stage phase change cooling on higher wattage cpu/gpu. Also guys who were benching FX processors had better results on good water cooling than single stage coolers. Especially when they were leaving large radiators outside the window during winter

 

[mackerel]

It's physics, or is it chemistry, to do the calculation I did on the energy required to heat and melt the ice, give or take some practical effects not considered like the environment warming it also. If I were to do this, I'd used several kg of ice so that will have a bit of mass behind it.

I don't regret selling my phase change cooler. What was around maybe 10+ years ago? There were two commercial systems, and I got one of them used. Can't remember the name. It wasn't powerful enough though. I had a 1.8A Northwood on it at the time and CPU temps were still above zero by the time you dumped the heat into it. I knew others more enthusiastic at the time who built their own two stage system from scratch. That was better

 

[Mandrake4565]

mackerel, myself, johan45 and a few others do with our H2O loop to get it sub ambient. In the winters I hang my radiator outside my office window. I can usually get the water temperature down to around outside ambient temperatures +2c. The other thing I do is put my rad in a cooler and cover it with dry ice. I've seen water temps as low as -20c like that. Take into account you still will need to protect against condensation, going sub ambient. As far as how much benefit you'll see, I've benched my FX 8350/ FX 6300 near 5.7 Ghz and my I7 4770k near 5.3 Ghz with this setup.

 

[Woomack]

My unit is 300W/-50°C and is overloading on higher overclocked FX, Radeon 7970/290X or anything else that has 300W+ ... as I said guys benching the same hardware on good water cooling had better results ( like Mandrake or Johan ). I'm not even trying with 7900X It's still good for 2-4 cores and something like 5820K but I'd rather get some dice for that.

 

[mackerel]

Given we're in mid-summer thoughts of winter cooling are far away.

I'll give dice another look, but last time I thought about it, it didn't seem easy or cheap to source even if it is a bit of fun for a day.

How much additive do you need to keep water liquid at -20C? More additive than water by that point?

 

[Mandrake4565]

Given we're in mid-summer thoughts of winter cooling are far away.

I'll give dice another look, but last time I thought about it, it didn't seem easy or cheap to source even if it is a bit of fun for a day.

How much additive do you need to keep water liquid at -20C? More additive than water by that point?

I use a 50/50 mixture of distilled water and automotive antifreeze, a 500gph pond pump and a kitty litter bucket for the reservoir. I believe Mr Scott uses windshield washer fluid but I'm not 100% sure of that. Here's a couple of pictures of my loop and Johan45's. I also have put my whole rig outside in the winter, though this isn't very good for hard drives.
My setup
Johan's

 

[Jeff G]

The last time I ran sub-zero temps, I used the winter blend windshield washer fluid. It worked well, and I think it was rated to -20C.
Condensation was always an issue though, it builds up on everything (tubing, block, fittings, basically anything touching the cold). Inverting will help, but remember that even the tubing will condensate and that water has to drip somewhere.

 

[Mr.Scott]

I use a 50/50 mixture of distilled water and automotive antifreeze, a 500gph pond pump and a kitty litter bucket for the reservoir. I believe Mr Scott uses windshield washer fluid but I'm not 100% sure of that. Here's a couple of pictures of my loop and Johan45's. I also have put my whole rig outside in the winter, though this isn't very good for hard drives.
My setup
Johan's

You would be correct.
Makes me good to about -30c, and my chiller wont go that low.

 

[batboy]

I still have a chiller from when I was a benchmarking team member. I have a drag racing gasoline cooler that worked pretty good at dropping the temps a little. I had to laugh at people in this thread calculating how much it'll drop temps. It wasn't a lot (maybe a few degrees) when you have voltages cranked up to insane levels and running a max overclocked system on the ragged edge of stability. But, sometimes a few degrees cooler can help get a slightly better benchmark and help win a competition. Yeah, it's a major hassle constantly dumping the ice melt water and adding more ice. You want to use small ice cubes or crushed ice in these chillers because it has more ice surface area in contact with the cooler. A brick of frozen ice will melt slower, but won't get your chiller as cold. From trial and error, I could bench for about an hour before adding another batch of ice. The cheap ghetto way is to fill a 5 gallon bucket with water and ice then drop a radiator from your system loop into the bucket (move the rad around while it's submerged to get all the air bubbles off the fins for better cooling).

Funny, we were doing all of this a decade ago and now people are talking about it again.

Here is a pic of the drag racing gasoline cooler I have (there are others on the market too).

 

[mackerel]

I'm not sure there is anything new, but they come in and out of fashion. Around 10 years ago or a bit more I've done peltiers and phase change also, but that seems like a bit more work than I can be bothered with these days.

 

[batboy]

Yeppers, you're right about things going in and out of fashion. Now, a ice water chiller will have the reservoir water below ambient temp, but if you're benching, the water in your computer loop will not be below ambient temp. Heck, put the comp in the bathroom and fill the tub up with ice and water or get one of those large plastic kiddy wading pool and use it. Think big... lol.

 

[GTXJackBauer]

Think big... lol.

This comes to mind.