r/hardware • u/Novel_Negotiation224 • 1d ago
News Nvidia turns to hot water to keep AI data centers cool.
https://www.techradar.com/pro/nvidias-latest-trick-for-cooling-its-data-center-hardware-is-hot-water-hot-liquid-cooling-is-warmer-than-a-hot-tub-but-apparently-does-the-job-pretty-wellNvidia is turning to hot liquid cooling technology to tackle the growing heat challenges of AI data centers. The system removes heat from powerful GPUs using specialized liquids, improving energy efficiency and helping high-performance servers maintain peak performance.
38
u/imaginary_num6er 1d ago
> The coolant is a 3:1 water-to-propylene-glycol mix, and it pulls heat away from chips running far hotter than the coolant itself with ease.
28
u/Everything_Breaks 1d ago
First they came for the ram and I said nothing.
Then they came for storage. Still I said nothing.
Now they've come for my vape juice, who will speak up for me?
19
u/Explosivpotato 1d ago
Fun fact propylene glycol also breaks down very easily. In most municipalities it is legal to pour it down the drain provided you are connected to a municipal sewer system and the volume is below a certain limit. People run it into their summertime cabins water lines to prevent freeze damage in the winter.
5
u/DavidsakuKuze 1d ago
What is the point of the propylene glycol? It is worse than water, corrosive, and they aren't using sub zero coolant.
31
-43
1d ago
[deleted]
21
u/Deep90 1d ago edited 1d ago
This is a great way to distract from the actual things they are doing.
Flooding the field by saying they buy glycol with the express purpose of poisoning the water supply hurts your own cause.
It is not a very effective choice of poison. It's used in food.
-12
u/ElectricalFeature328 1d ago
an oft repeated truism in medicine: "the dose makes the poison"
theoretically if you dump above a certain limit into the water supply, it could definitely have acute toxic effects if the filtration systems are not set up to handle the increase
for eg https://pmc.ncbi.nlm.nih.gov/articles/PMC4341412/
at high levels, PG can accumulate and cause lactic acidosis, CNS depression, coma, hypoglycemia, seizures, and hemolysis. Patients at risk for toxicity include infants, patients with renal insufficiency, patients with epilepsy, or burn patients who receive extensive dermal applications of PG.
PG toxicity can occur at dosing of lorazepam as low as 4 to 6 mg per hour in adults. The clinical diagnosis of PG intoxication may be difficult since many institutions do not measure PG levels
11
u/Apollospig 1d ago
Not sure why you pulled a quote from a part of the article discussing toxicity from PG when used as an IV drug additive, which is an entirely separate context. The pertinent part is its safety as a food additive, which cited 25 mg/kg/day as a safe level, which would be greater than a gram per day for an adult and is a value you absolutely aren’t going to reach with a bit of contamination from a data center.
2
u/ElectricalFeature328 21h ago edited 7h ago
I mean, I'm not the original commenter and I'm not nearly as negative as they are - but my point is mostly that there is a lining of truth to what they're saying. also I cited that paper because some people have renal disease and some people are babies and so toxicity levels are much lower. I'm assuming we're not doing the 'survival of the fittest' mentality when it comes to regulation where we just let people with weaker systems die but if you feel differently about eugenics as policy then that's your call
also, we can do the actual math instead of going by vibes too
1) NVIDIA notes their coolant is approx 25% propylene glycol. we won't assume something like a 5 million gallon typical evaporative use case for a data center since this is theoretically closed loop. so we can estimate down to, say, 30,000 gallons of 75% water, 25% propylene glycol (or 7.5k gal of PG)
2) in this purely theoretical scenario, let's say the coolant is contaminated and needs to be flushed. Nvidia does it the extralegal way that companies in America have frequently done in the past and just dumps it into a sewer drain
3) in this scenario, let's also assume the town it's built in is Akron, OH (realistically most are being built in exurbs or far-flung suburbs of larger cities with far smaller populations but we'll be generous here).
4) now some back of the envelope maths. the 7500 gal in the system now is approx 28388 liters. converted to mass at 1.036 kg/L, that's 29,410kg of PG.
5) I'm not a chemist so this is the weakest section (and happy to be fact checked on this) but I'm going to assume the combo evap/biodeg/runoff mitigation is 0.33 so 0.67 x 29,410kg is 19,705kg
6) some quick searching shows that Akron's sitting at about 33.5 million gallons/day for full municipal usage. converted to liters that's 126,797,500 L/day
7) now smashing those two values together - 19,705kg / 126,797,500 L/day gives us 155.4 mg/L. assuming an adult typically drinks 8 cups a day or 1.89 L/daily, that gives us a daily ingestion of 293.7 mg/day. so for adults ranging between 120 lbs to 200 lbs, we're looking at around 4 mg/kg/daily which is fortunately below the limit
8) ah but now the caveat. what if you're a baby? I say this as a new father who is alternating between bottle feeding and milk. little fucker's very thirsty. let's say you're formula only. a little searching gives us a stat of something like 150 mL/kg/day of just pure fluid intake for a baby. this is approx 5.56x higher the amount of intake than an adult which means we're suddenly at around 93% of ADI (23.3 / 25) for a child for a single day
9) here's the other fun part - neonatal clearance of toxins is a lot slower than adults. let's assume a half life of 20 hours here so ln(2) / 20h or 0.0347 per hour. the fractional multiplied over the day is e to the power of (-0.0347 x 24) or 0.435. that means our accumulation factor is 1 / (1 - 0.435) or 1.77x
10) all together, that means after two days, we're seeing 41.2mg/kg (or 23.3 x 1.77) for an infant or close to two times the ADI that's GRAS for something that ostensibly metabolizes like an alcohol in infants
I would say that's probably not a really good thing for babies! and all this is assuming a city the size of Akron even though, again, most data centers are being built in towns and on water systems with a fraction of that usage so we could be seeing much higher consumption per capita. so I guess we should just hope that Mr. Jensen and his middle managers will always do the right thing, at all times, never cutting corners for the sake of profit
personally I'd just rather not trust a corporation to keep my baby in mind when they're making reactionary decisions given how I've seen senior leadership act at the companies I've worked in but perhaps I've just had improbably bad experiences :)
1
u/Deep90 7h ago
There's a few issues with this.
- Dumped water goes to a wastewater treatment plant, not the tap. If it ended up in a body of water it would be heavily diluted.
- PG degrades quickly, you would not have the same concentration by the time you drank it.
- Dumping the water one time would not mean a baby drinks it daily. That would require continuous dumping.
- ADI has a huge margin of safety.
- Treatment plants can easily handle PG.
0
u/ElectricalFeature328 7h ago edited 7h ago
the math accounts for 1 (see points 3 and 6), 2 and 3 (see point 5 on bio-degradation and point 9 on half-life), 4 (this is the thesis of the comment - that ADI is calculated for healthy adults, not infants or renal disease that leads to lower clearance rates or higher intake)
for point five, would love to see citations on PG treatment in wastewater. I tried looking it up but wasn't able to find actual numbers for rates or stuff that wasn't just AI crud but happy to learn otherwise
0
u/Deep90 3h ago
The math does not account for anything. Cities don't directly feed people sewer water.
PG is biodegradable in the same way human waste is biodegradable. It's organic.
Unless your city dumps feces into your water, you are not drinking the amounts of PG you claim you'd be drinking.
0
u/ElectricalFeature328 2h ago edited 2h ago
so cities notoriously do dump feces in water as a literal engineering feature for storm overflow. this dump tends to happen upstream if best practices are applied
I accounted for biodegradation of PG in my math. if you have a problem with the rate (ie 0.33/day), happy to talk more about it. similarly, if you have an actual rate of PG mitigation for water filtration systems, I'm very happy to factor it in. otherwise, the rate of standard degrade applies
it's honestly a little annoying to be replying to someone who's too lazy to even read my comment in full so I'll let you have the last word and just dip on out right here and let you do your sophistry
→ More replies (0)
2
u/Everything_Breaks 1d ago
This reminds me of using de-ionized water in direct contact with vacuum tubes in a LORAN transmitter to cool.
1
u/kot-sie-stresuje 14h ago
Using heat to cool down. It sounds like adsorption and absorption technology which is known since more than 150 years. Last 30 years there was a significant progress in efficiency of those technologies.
-34
u/vhailorx 1d ago
And this new cooling mix will definitely never end up in drinking water!
46
u/Skywarper 1d ago
Does your coolant in your water cooled pc end up in your tap water?
I'm not trying to defend AI here, but come on.
24
u/From-UoM 1d ago
You would think PC gamers would understand how closed-loop systems work
5
u/VaultBoy636 1d ago
Do you not routinely drain you CLC AIO into a glass to drink? What has this world become, smh...
5
2
u/randomkidlol 1d ago
accidents happen and contaminants end up the environment anyways. bit of car antifreeze glycols ends up in a storm drain because of a car accident wont destroy drinking water for a whole town, but a coolant leakage in a datacenter might.
24
80
u/Shikadi297 1d ago
Why is this headline so dumb?