It is not expensive, nor is it highly technical. It's not like we're factoring in latency and crosstalk...
Read a quick howto, cruise into Home Depot and grab some legos off the shelf. Far easier to figure out than executing "hello world" from zero.
Which is used as "what the heck" but it's direct kanji translation is one body.
Residential electrical is dangerous. Maybe you electrocute yourself. Maybe you cause a fire 5 years down the line. Maybe you cause a fire for the next owner because you didn't know to protect the wire with a metal plate so they drill into it.
Having said that, 2 4090s will run you aroud $5,000, not counting any of the surrounding system. At that cost point, hireing an electritian would not be that big of an expense relativly speaking.
Also, if you are at the point where you need to add a circut for power, you might need to seriously consider cooling, which could potentially be another side quest.
There should be an easy/reliable way to channel "waste heat" from something like this to your hot water system.
Actually, 4 or 5 kW continuous is a lot more than most domestic hot water services need. So in my usual manner of overcomplicating simple ideas, now I want to use the waste heat to run a boiler driving a steam engine, perhaps to directly mechanically run your air conditioning or heat pump compressor.
Stuffed the homelab next to the air intake of the water heater, now when I need hot water my water heater sucks the heat out of the air and puts it into the water.
It's obviously not 100% efficient, but at least it recaptures some of the waste heat and decreases my electrical bill somewhat.
These aren't power requirements that are insurmountable. They would get pricey though and I wish my rig for computing would use something around .1kW under load...
Using the heat from PCs would be nice. I guess most just use them as electrical heaters right now.
If you screw it up and need to file a claim, insurance can’t deny the claim based solely on the fact that you performed the work yourself, even if you’re not a certified electrician/plumber/whatever.
What you don't want to do is have an unlicensed friend work on your home, and vice versa. There are no legal protections, and the insurance companies absolutely will go after you/your friend for damages.
Edit: sorry this applies to owned property, not if you’re renting
What is common here, in the handy crowd at least, is to do your own electrical, plumbing, gas work and leave it open and accessable for a licenced professional to check and sign off on.
You're still paying for an hour or two of their time and a surcharge for "taking on the responsibility" but it's often not an issue if the work is clean, to current code, and sanity tests correct (correct wiring, correct angles on plumbing, pressure testing on gas pipes).
_This_ is the claim that is extraordinary. I'm not saying that the government would bust down my door for doing work on my own home, but rather that the insurance company would then view that work as uninsured.
The entire business model of insurance agencies is to find new, creative, and unexpected ways to deny claims. That is how they make their money. To claim that they would accept liability for a property that's had uninspected work done by an unlicensed, untrained, unregistered individual is just that - extraordinary.
https://www.montgomerycountymd.gov/DPS/Process/combuild/home...
Granted, if you actually do unlicensed work in your house, no one will know. But it is still illegal.
Re: cooling; I have an AC vent directed on the setup, plus planned out in-out in the most optimal way possible to maximize cooling. I have installed like 20 more fans since taking these pictures :D
The instinct to not touch something that you don't yet deeply understand is very much an engineer's instinct. Any engineer worthy of the title has often spent weeks carefully designing a system to take care of the hundreds of edge cases that weren't apparent at a quick glance. Once you've done that once (much less dozens of times) you have a healthy respect for the complexity that usually lurks below the surface, and you're loathe to confidently insert yourself confidently into an unfamiliar domain that has a whole engineering discipline dedicated to it. You understand that those engineers are employed full time for a reason.
The attitude you describe is one that's useful in a lot of cases and may even be correct for this particular application (though I'm personally leery of it), but if confidently injecting yourself into territory you don't know well is what being an "engineer" means to you, that's a sad commentary on the state of software engineering today.
If you know nothing about basic electric work or principles, sure - spend the $500 to have an electrician add a 30 or 50A 220V outlet near your electric service panel. Totally reasonable to do as it is indeed dangerous to touch things you don’t understand.
It’s far less complex and less dangerous than adding an EV charge point to your garage which seems to be quite common for this crowd. This is the same (less, since you typically have a lot more flexibility on where to locate the outlet and likely don’t need to pull through walls) complexity as adding a drop for an electric stove.
Where the “home electric hackers” typically tend to get in trouble is doing stuff like adding their own generator connection points and not properly doing interlocks and all that fun stuff.
If you can replace your own light switches and wall receptacles you are just one step away from adding an additional branch circuit. Lots of good learning material out there on the subject these days as well!
As a hobby, I restore pinball machines. A modern one is extremely careful about how it uses power, limiting wall current to a small, normally-sealed section of the machine. And even so, it automatically disables the lower-voltage internals the moment you open the coin door. A 1960s machine, by contrast, may not have a ground at all. It may have an unpolarized plug, and it will run wall current all over the place, including the coin door, one of the flippers, and a mess of relays.
In the pinball community, you'll find two basic attitudes toward this. One is people treating electrical safety about as seriously as the people who design the modern machines. The others is people who think anybody who worries about a little wall current are all pussies who don't have the balls to work on anything and should just man up and not worry about a little 120V jolt.
The truth is that most people here are not engineers of any sort. We're software developers. We're used to working in situations where safety and rigor basically don't matter, where you have to just cowboy ahead and try shit. And that's fine, because control-z is right there. I've met people who bring that attitude to household electrical work, and they're fucking dangerous. I know one guy, quite a smart one, who did a lot of his own electrical work based on manliness and arrogance, and once the inspector caught up with him, he immediately pulled the guy's meter and wouldn't let him connect up to the grid again until a real electrician had straightened it all out.
It's true that this stuff is not that hard to learn if you study it. But an architect friend likes to say that the building code is written in blood, meaning that much of it is there because confident dumbasses managed to kill enough people that they had to add a new rule. If people are prepared to learn the rules and appreciate why they're there, I'm all for it. But if they do it coming from a place of proving that they're not "so afraid of residential power", that's a terrible way to approach it.
That being said, it's still very easy not to kill yourself with 120/230V: just shut down the power before touching anything.
Some old serial ports had 12V and a high max current. The DIY things you attached here were prone to kill your mainboard.
Voltage/current is either 0 or 1. Anything higher kills software developers instantly.
In the real world you would plug them into a PDU such as: https://www.apc.com/us/en/product/AP9571A/rack-pdu-basic-1u-...
Each GPU will take around 700W and then you have the rest of the system to power, so depending on CPU/RAM/storage...
And then you need to cool it!
Cooling is its own story... Man, figuring out this process was hella of a journey
Back when I worked at a high-availability data center, all of our servers had dual psus, plugged into seperate circuits.
The transformer in the PSUs should electrical isolate the mains voltage from the low voltage side, so you aren't going to cause a short across the two circuts.
The only risk I see is a cascade failure, where the increased load on the second circuit causes its breaker to trip.
Which is all to say its possible in a residential setting, just probably expensive.
I wrote a blog on reducing the power limits of nvidia gpus. Definitely try it out. https://shelbyjenkins.github.io/blog/power-limit-nvidia-linu...
I would say that power limiting is a potential work around, and it should work perfectly fine for inference, but when it comes to trainning you will want to squeeze every ounce of power. So, depends on your goal.
What CPU/Mobo/Storage are you running with those two 3090s for a 700w to work? I am gonna say, if at any point you're pushing more than 500w out of that PSU, you might be risking the 80% safety rule. I would have at least used a 850w just to be safe with two 3090s + rest of hardware.
I'm curious, how do you use e.g. a washing machine or an electric kettle, if 2kW is enough to flip your breaker? You should simply know your wiring limits. Breaker/wiring at my home won't even notice this.
Boiling 1 liter takes like 2 mins. Most Americans don’t have kettles because they don’t drink tea.
You're correct that the dryer is on a larger circuit, though.
You think that this is "just fine" because you've never experienced the glory that is a 3kW kettle!
1.5kW must be absolute agony
I've never seen a dedicated circuit for dryers in Australia, and I've lived in probably a dozen different properties. Ovens, aircon, hot water, bathroom heat lamps often have dedicated circuits, though.
If that wasn’t the limit though, the fact that the machine is currently a space heater at 2 liquid cooled 4090’s would be.
16 amps x 120v = 1920W, it would probably trip after several minutes.
16 amps x 230v = 3680W, it wouldn't trip.
FYI, I can handle electrical system design and sheet metal enclosure design/fabrication for these rigs, but my software knowledge is limited when it comes to ML. If anyone's interested, I'd love to collaborate on a joint venture to produce these rigs commercially.
As I mentioned in my reply to OP, very doable as long as you do your research. The only thing I did not do was not doing the installation itself because I was not comfortable with it, but I pretty much had everything named to the contractor, and even how I would have gone about the installation process was exactly how he did it.
Hit me up on Twitter or Email, we can chat ideas about this venture
So, as mentioned on the article, I actually have installed (2) 30amp 240v breakers dedicated entirely for this setup (and the next one in case I decide to expand to 16x GPUs over 2 nodes lol). Each breaker is supposed to power up to 6000w at ease. I also installed a specific kind of power outlet that can handle that kind of current, and I have done some extreme research into PDUs. I plan on posting about all of that in this series (part 3 according to my current tentative plans) so stay tuned and maybe bookmark the website/add the RSS feed to your digest/or follow me on any of the socials if this is something that you wanna nail down without spending a month on research like me :'D
Hell most kettles use 3kw. Tho for a big server I'd get it wired dedicated, same way power showers are done (7-12~ kW)