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Data centers are transitioning from AC to DC

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Re: Data centers are transitioning from AC to DC

#231

Post by nancyminusone »

ta9000 wrote: post #160
teleforce wrote: post #121

Earlier quoted context omitted.

>It is absolutely stupid to talk about this as edisons revenge. If Tesla had the modern high power transistors needed to get high voltage dc out of the ac produced from a spinning turbine he would be all for high voltage dc too. This! The soon people realized these facts the better. The pervasive high rise buildings did not happen before the invention of modern cranes. Exactly twenty years ago I was doing a novel res…

Does that mean when we run out of Ga there are no more LED TVs?

Except for gaseous hydrogen and helium, and some spacecraft, all other atoms remain on the earth and are recoverable with enough energy and effort.

Re: Data centers are transitioning from AC to DC

#232

Post by myrmidon »

mschuster91 wrote: post #223
myrmidon wrote: post #217

Earlier quoted context omitted.

Sidenote: Whenever someone tells you that (vital) reserves of some ressource are going to run out soonish (implying drastic consequences), you should be extremely skeptical: Such predictions have an abysmal historic track record, because we tend to find workarounds both on the supply side (=> previously undiscovered reserves) as well as flexibility on the demand side (using substitutes). This applies historically for…

> Such predictions have an abysmal historic track record, because we tend to find workarounds both on the supply side (=> previously undiscovered reserves) as well as flexibility on the demand side (using substitutes). That's a classic example of the "preparedness paradox" [1]. When no one raises the alarm in time or it is being ignored, resources can go (effectively) exhausted before alternatives can be found, or co…

I don't see the Guano industry as a straight counter-example, it even illustrates my point:

If you had made predictions/scenarios in 1850 based on Guano deposits running out within a decade or two, you would have mispredicted completely, because a lot of the industry just transitioned to sodium nitrate (before synthetic fertilisers took over). Nowadays media landscape would've gladly made such doom-and-gloom predictions for global agriculture back then.

I completely agree that quickly depleting reserves often indicate non-sustainable pricing for ressources (which is obviously bad long term), but that is very different from sudden collapse.

Re: Data centers are transitioning from AC to DC

#233

Post by ndsipa_pomu »

Imustaskforhelp wrote: post #194
elar_verole wrote: post #171

Earlier quoted context omitted.

People need heroes. It's like the Keanu Reeves or Musk era, all the ""badass"" stories about this or that soldier / local hero / w/e that are very often overblown and get further and further away from the initial facts every time they resurface. No hate here, just noticing there is a weird visceral need to distill stories to their most essential, good vs evil, and the Tesla v Edison thing embodies this perfectly I th…

Keanu Reeves and Nikola Tesla to a degree as well, are decent figures. Aside from all the cult classics Keanu is part of like john wick and the matrix, even discounting that, he is a good person in it of itself who is genuinely humble and might be one of the best persons within hollywood. What I feel pissed about is that people like Andrew Tate and others like them took the concept of Matrix and the contributions Kea…

Whilst I agree that Keanu is a most excellent human, he was hardly responsible for the concept of the Matrix. In my opinion, Philip K Dick was a major influence (I'm a fan and consider him the prophet of the modern age), though Gibson's Neuromancer was likely a big influence too. (Also, there's the old Doctor Who episode "The Deadly Assassin" which features the Matrix).

It always seems to me that the far right are bereft of original ideas and always co-opt other pre-existing concepts. There's exceptions, but I always find that right wing works are always lacking humour or irony (c.f. Ayn Rand's works).

Re: Data centers are transitioning from AC to DC

#234

Post by card_zero »

nkrisc wrote: post #214
bananaflag wrote: post #206

Earlier quoted context omitted.

On the other hand, it is possible to run out of a metal when all of it is either somewhere in some device or scattered among landfills (i.e. not concentrated in a place like a mine).

That’s still not running out. It’s still there, just more effort to get.

"At 10 parts per quadrillion, the Earth's oceans would hold 15,000 tonnes of gold", says the Wikipedia page on gold.

I'm inclined to think we've lost that gold.

Re: Data centers are transitioning from AC to DC

#235

Post by myrmidon »

reylas wrote: post #225
myrmidon wrote: post #217

Earlier quoted context omitted.

Sidenote: Whenever someone tells you that (vital) reserves of some ressource are going to run out soonish (implying drastic consequences), you should be extremely skeptical: Such predictions have an abysmal historic track record, because we tend to find workarounds both on the supply side (=> previously undiscovered reserves) as well as flexibility on the demand side (using substitutes). This applies historically for…

I always add "cheap" to the sentence. It seems they are always talking about the cheap version of anything. Going to run out of water? Or are we running out of the "cheap" version of water that does not have to be processed?

This is a valid point: quickly depleting reserves often indicate that pricing is not sustainable. Which is bad.

But non-sustainable pricing is very different from "cataclysmic collapse", and too many people expect the latter for too many things, which is just not realistic in my view (and historical precendent makes a strong case against that assumption, too).

A society where water prices gradually increases to "reverse-osmosis only" (instead of "pump-from-the-ground-everywhere") levels is very different from a society where water suddenly runs out.

Re: Data centers are transitioning from AC to DC

#236

Post by asah »

teleforce wrote: post #121
hristov wrote: post #9

It is absolutely stupid to talk about this as edisons revenge. If Tesla had the modern high power transistors needed to get high voltage dc out of the ac produced from a spinning turbine he would be all for high voltage dc too. Tesla understood that high voltage was needed for efficient long range transmission. He also understood that transformers were the inly remotely efficient way to climb up to and down from thes…

>It is absolutely stupid to talk about this as edisons revenge. If Tesla had the modern high power transistors needed to get high voltage dc out of the ac produced from a spinning turbine he would be all for high voltage dc too. This! The soon people realized these facts the better. The pervasive high rise buildings did not happen before the invention of modern cranes. Exactly twenty years ago I was doing a novel res…

> The pervasive high rise buildings did not happen before the invention of modern cranes.

yyy! if we're going to wander off-topic :-) then I should mention elevators, water pumps, fire suppression including fire truck ladders and more! :-)

Re: Data centers are transitioning from AC to DC

#237

Post by sobjornstad »

jacquesm wrote: post #68
ericd wrote: post #45

Earlier quoted context omitted.

heh man, I'm glad you got out of that easy, I definitely wore safety glasses 100% of the time after my experience. I think a lifetime of experience with dangerous wall outlets and harmless little 1.5V/9V DC cells teaches us the wrong lessons about DC safety. I've since heard stories of wrenches exploding when they fall across EV high voltage battery terminals. Wrenches aren't supposed to be explosive. The electrician…

Those harmless 9V DC cells can do a lot of damage if you use them right.

This reminds me of the sailor who [decided](https://darwinawards.com/darwin/darwin1999-50.html) to measure his internal resistance by pushing probes through the skin on his thumbs and electrocuted himself with the 9V multimeter battery.

Re: Data centers are transitioning from AC to DC

#238

Post by chromacity »

pjdesno wrote: post #227

90% of the power in our academic data center goes 13.8kV 3-phase -> 400v 3-phase, and then the machines run directly from one leg to neutral (230v). One transformer step, no UPS losses, and the server power supplies are more efficient at EU voltages. But what about availability? If you ask most of our users whether they’d prefer 4 9s of availability or 10% more money to spend on CPUs, they choose the CPUs. We asked t…

> and then the machines run directly from one leg to neutral (230v)

And then every machine has a switching power supply to convert this to low-voltage DC, and then probably random point-of-load converters in various places (DC -> AC -> DC again) for stuff like the CPU / GPU core, RAM, etc. Each of these stages may be ~95% efficient with optimal load, but the losses add up, and get a lot worse outside a narrow envelope.

Re: Data centers are transitioning from AC to DC

#239

Post by fecal_henge »

eqvinox wrote: post #210
fecal_henge wrote: post #207

Earlier quoted context omitted.

We go -48 -> 48 -> 12 -> 3v3,1v8 etc etc. If you went 48 straight to POL voltages then you would have horrific converter performance.

> If you went 48 straight to POL voltages then you would have horrific converter performance. What's horrific converter performance in numbers? An isolated flyback (to 12V) should be able to hit >92% and doesn't care if it's fed -48V or +48V or ±24V. TI webench gives me 95% though I'd only believe that if I'd built and measured it. What's the performance of your -48V → +48V? [with the caveat that these frequently req…

-48 to 48 claims something like 97% (load dependent of course). It also needs to arbitrate between two input supplies for glitchless redundancy, plus have PM bus and other spec mandated stuff. There is no technical reason why you cant go -48 -> 12 as you state with good efficiceny, but we cant get hold of a part that ticks all the boxes.

Horrific performance by my definition would be 48v to say 1v. We only realistically use buck topologies for POL supplies. Such a ratio is really bad for current transients, not to mention issues like minimum on times for the controller.

Re: Data centers are transitioning from AC to DC

#240

Post by superxpro12 »

hristov wrote: post #9

It is absolutely stupid to talk about this as edisons revenge. If Tesla had the modern high power transistors needed to get high voltage dc out of the ac produced from a spinning turbine he would be all for high voltage dc too. Tesla understood that high voltage was needed for efficient long range transmission. He also understood that transformers were the inly remotely efficient way to climb up to and down from thes…

Yeah this isnt an argument. It was far simpler to wrap some copper wire around a chunk of metal than it was to fire up a mosfet fabrication plant in the 1800's.

You can have the best idea in the world, but if you cant manufacture it you're SOL.

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