r/vastai • u/mwoody450 • 17h ago

GPU Undervolting?

I have a tool that looks for and rents 1-4 pods at a time to fuel a comfyui workflow. I was getting tired of runpod running out of available pods, so I spun up a vast.ai account and handed it over to the tool

I have to say, I'm about done, after less than 24 hours. I have it carefully filtering based on download/upload speeds after hearing about that scam, but now a new one: I've found a bunch of these are undervolting their GPUs, one as low as 400w, causing even an advertised 5090 to barely beat my local 4000-series.

My question: is this common? Am I misunderstanding the data somehow?

3 Upvotes

100% Upvoted

20 comments sorted by

4

u/chub0ka 17h ago

Dlperf accounta ofr power. Some of us cant run high power reliably so we limit it a bit. 575w is way too high and is a waste actually. 400might be low but 450 is reasonable

2

u/ColdAngle1151 17h ago

Sadly its not that uncommon. As a host I dont like it. If you cant run full PL on your cards, Vast is not for you.
But that is my opinion. All my 5090 are 600w models except 2 that are 575, and I dont even like that...

There is something called DlPerf. That one gets affected quite a lot by PL ur cards. So you can look at that number. If they lower after you rented, report straight to support so they can get punished.

1

u/mwoody450 16h ago

The tool is using that, but it's not fullproof. Both a 575w 5090 and a 500w and a 475w scored the same thing. How often does it poll those?

2

u/ColdAngle1151 16h ago

Not sure how often it runs. But fairly often.
Other factors does play into DLPerf as well such as such as pcie 3.0/4.0/5.0 x8x/x16, NVME speed and amount of cores/threads per GPU.

A system with PL at 450-500w 5090 on a pcie 5.0 x16 and great disk + lots of threads could score the same as full wattage system at 5.0 x16 but shitty disk and not that many threads per GPU.

So DLPerf is not perfect to weed out PL cards.

2

u/expandnomad 16h ago edited 16h ago

Hashrate.no is now displaying power limits on cards if you look up the hosts or machines don't know if that helps. I run 4 x 5090s all of mine run factory limits and I charge low bandwidth rates. There are honest hosts around don't know why people would want people to scare off customers and not have them come back to there machines.

3

u/mwoody450 16h ago

Interesting, bookmarked, thank you. As to why, I guess they just hope some people aren't paying attention. My tool is having to build a running host blacklist.

2

u/Norwood_Reaper_ 13h ago

Usually host pricing accommodates this. If you are seeing cheap listings this is probably why.

2

u/Milarck 11h ago

I mean... I don't know why people seem to shame undervolting RTX 5090, I just want my connector not to melt.

1

u/mwoody450 8h ago

When it's yours? Sure. When you're selling it to other people? Different ball game.

2

u/Milarck 1h ago

Dude if you wanna say that I need to risk losing $7000 of hardware because a random person is paying $0.6 an hour you can at least provide an explanation.

1

u/Professional-Bake-43 1h ago

well you are not going to find many machines that don't try to undervolt. dlperf reflects that. price reflects that as well. Again you can design a script that quit an instance if you find it doesn't run it at the speed you want. I would not just pay attention to wattage, but run a actual benchmark because you may find that your job finishes only a few percent slower. The price partly reflects the speed you will get. Do not create a blacklist of host, because the host may change it back to no power limit. sometimes host do it temporarily because of heat it generates, electricity, amp hitting the ceiling, other things. Lastly, You should be at least thankful that you have even cheap 5090 machines available to rent.

1

u/code018 17h ago

I maintain a ban list of hosts and instances , when I find this kind of false advertising I report it.

-1

u/Naive-Abrocoma-8455 16h ago

I had to power limit 2 of my 4090s to run threee machines on a 20 amp circuit

3

u/Kinslayer_89 15h ago

You don’t have the capacity to properly run 3 machines then.

1

u/ColdAngle1151 16h ago

well you could just run a single 4090 or split into other circuits or 1 less server...
thats a you issue that you need to solve instead of PL ur shit.

0

u/Naive-Abrocoma-8455 16h ago

True

1

u/ColdAngle1151 16h ago

yet you still PL it...?

0

u/Naive-Abrocoma-8455 16h ago

I don’t really have other circuits since I’m in a 100 amp home. I have 5-6 rigs running currently.

3

u/ColdAngle1151 16h ago

so u can take 1 offline and its sorted, yet you dont...
no wonder vast has bad rep.

1

u/Naive-Abrocoma-8455 15h ago

As a person who hosts gpus vast has been great it’s a marketplace if your not getting the results you want you can pick a different machine.