Dave Lee recently held a livestream with machine learning expert James Douma on his YouTube channel “Dave Lee on Investing.” For those who missed it, here’s a recap of the live stream. The topics were centered around Tesla FSD Beta, Tesla AI Day, and the future of autonomous driving.
The first thing they talked about was this tweet below by Dennis Hong, a professor of mechanical & aerospace engineering at UCLA and the director at the Robotics & Mechanisms Laboratory. Teslarati noted that this could be Tesla’s in-house Dojo Chip, which is used along with a computer architecture optimized for Neural Net Training to improve Tesla Full Self-Driving/Autopilot. In the livestream, Dave asked James what he thought the chip was.
— Dennis Hong (@DennisHongRobot) August 3, 2021
“It’s a packaging technology for putting a bunch of chips together, close — a bunch of large chips — and getting heat out of the package.”
Note: IC is a reference to collector current.
“Commercial ICs just get potted in plastic and they get soldered down to a board. And then you have to run them at a power density that is low enough that you can get the heat out. And there are some exceptions. you know, like people who get fancy gaming PCs or if you have a GPU. You have a chip where the chip is already pretty expensive and you really want to get everything you can out of it.
“So you want to crank up the clock, right, but to get it to run at a higher frequency, you have to run it at a higher voltage. The amount of current sloshing around the IC goes up so the amount of heat goes up and then silicon only works in a fairly narrow — it only works well in a fairly narrow range of temperatures.
“So if you want to crank up the clock, right, and if you want to pump lots of data in and out of your chip, it gets really hot. You have to figure out how to get the heat out. The hottest chips — the ones you care the most about — they typically get big heat sinks on them in a PC.
“Like your laptop, you know, it’ll have a heat sink sitting on top of the IC and will blow all over it and all that is just to keep the IC at a temperature where it’ll continue to operate well. When you really want to push chips hard, the thermal constraint becomes a really big deal. Not only do you have to get lots of power into this chip, you have to get lots of data in the chip, lots of data out of the chip. And it’s making all of this heat, and you gotta get the heat out of the chip. Getting all of this stuff in and out of the chip is a very challenging mechanical design problem.
He further explained that if you really want to get as much as possible out of a piece of silicon, another approach is to go very sophisticated packaging solutions that allow one to operate the IC at extremely high power densities while getting the heat out safely. This photo in the tweet looks like such a solution to James. He explained that the top piece and bottom piece in the photograph looked like heat plates. Dave asked if this was normal and James explained that it wasn’t.
“This is exotically unusual.”
Dave asked James from his experience what was going on with Tesla and how he sees FSB Beta 9.0. Is he noticing differences from previous versions and how is it evolving? He also asked if James noticed any areas needing improvement and what his overview was?
James noted that he didn’t have version 8 or 9, and that he spent a few hours with Dave in 9. He explained that he didn’t feel as if he had the experience to share broad general thoughts about it as a result. Here is what he did say:
“I’ve watched a decent number of videos. People’s experience on 8 and on 9 vary a lot. There are people who definitely struggle and there are people who are absolutely delighted with it and they feel like it’s working great. And some is undoubtedly because people have different expectations and comfort zones with respect to what the car can do when they’re driving it.
“But also a lot of has to do with the characteristics of the place that they happened to do their driving. Or the kind of driving they do. If you have a left turn across high-speed traffic into the community you live in and that’s a thing you drive every single day and it doesn’t do that well, and you’re using FSD when you’re coming home late from work and there’s a ton of traffic and your car might kill you, yeah, you’re gonna have a different experience than someone who uses it only on vacations or who spends a lot of time on empty roads on the highway, or if you’re a night owl and you use it at night — that kind of stuff.
“It’s not done for sure. It definitely has a lot of ugly spots to it.”
James also noted that he was surprised by the amount of polish he saw when the first 8.0 videos came out.