Pi 5 overclocking: Silicon Lottery

https://www.jeffgeerling.com/blog/2024/important-consideration-about-pi-5-overclocking

by goranmoomin • 2 years ago

101 56 2 years ago

moffkalast3• 2 years ago

Speaking of Geerling testing Pi 5 things, is it just me or is it super weird that the uPCity PCIe breakout board hasn't been put on sale yet? I think it's almost half a year since he got it working in a pre-release state.

tuetuopay3• 2 years ago

I recently went on the lookout for this board and it is still unavailable. All I could find were M.2 adapters. I guess the market for full-size PCIe is tiny compared to the M.2 one.

Anyways, I ended up making my own and it works great. No fuss, no wait, no complications.

moffkalast3• 2 years ago

Ah you mean going the Pi Port -> M.2 hat -> M.2 to PCIe riser route? I suppose that should work. Any bandwidth issues?

geerlingguy3• 2 years ago

I keep pushing Pineberry Pi to release that—apparently they're still working on it—and 52Pi pre-announced something too...

But so far there's no straight PCIe expansion board available to purchase yet. It is a slimmer market than 'NVMe on top' or other more standard use cases, but it's one I think could expand as people do weird things with the Pi 5.

moffkalast3• 2 years ago

Oh cool I haven't heard of that one, I see you have it listed: https://pipci.jeffgeerling.com/hats/52pi-pcie-x1-slot-hat.ht...

Looks way more compact and well thought out in terms of mounting so definitely seems like the better option once it's released.

TehCorwiz2• 2 years ago

My Pi 5 is still back ordered. :(

natebc• 2 years ago

I ordered one from pishop.us just last Friday that arrived via USPS on Monday morning. Might look around some and see if you can just order from a different vendor.

techwiz1372• 2 years ago

For the time it took them to develop it, the performance is really lackluster. I would've definitely wanted an OrangePi 5 equivalent performance, but with the mature software of the RPI.

TehCorwiz2• 2 years ago

Yeah, I ordered from Sparkfun. I've had good experiences with them in the past, but it's a little frustrating seeing it available elsewhere. I ended up reaching out about it.

teamonkey• 2 years ago

https://rpilocator.com/?cat=PI5

geerlingguy3• 2 years ago

They've been on the shelf (well, behind the counter) at Micro Center for a month or so now, never seen them out of stock. It seems like all the models are available at one or two retailers at minimum now, via rpilocator.com.

Are you in the US, Canada, or EU? Outside of those places, there may still be some delays in getting stock to meet demand.

duffyjp• 2 years ago

Oof, $80 is encroaching on Aliexpress N100 Mini PCs and used "Tiny/Mini/Micro" territory.

I have the original and updated Pi Zero W-- unbelievable bargains at ~$15 but if I needed any horsepower I think I'd rather have an x86_64 so I can run whatever.

bobim2• 2 years ago

Idle consumption made me lean toward a rk3588 vs a n100. Half the single thread performance though. Supported by dietpi, so no issue with the os.

MuffinFlavored• 2 years ago

The result of that 3.0 GHz overclock? A marginally-improved Geekbench 6 score of 1662, versus 1507 with no OC. To achieve that 10% speedup, it ate up about 20% more power, so efficiency-wise, it's not worth it.

What effect would running an overclock like this permanently have on longevity? Is it even worth thinking about "longevity" of chips?

Obviously stability suffers but for example... how much? Author was able to get a Geekbench 6 benchmark to pass. If they tried 100 times, would it be expected that a non-zero amount would fail?

techwiz1372• 2 years ago

Of course! These are like BGA or something similar, the solder will crack after some number of on/off/cool/heat cycles.

If voltage is raised we enter the realm of electromigration, though not sure how relevant it is for such a minuscule OC.

As for stability, yes. If the voltage is not sufficient there will be stability issues which will require further raising it, thus raising temps and requiring more power which you can't be sure if you could deliver. And then of course electromigration.

0x457• 2 years ago

Of course! These are like BGA or something similar, the solder will crack after some number of on/off/cool/heat cycles.

This was mostly happening during the transition to lead-free solder. Today, component should fail earlier than BGA.

sweetjuly2• 2 years ago

Unfortunately, most of the useful data you want about wearout is locked behind tech NDAs so nobody will be able to offer specifics here.

But in general, the way you tend to end up with wearout is through electron migration ("electron wind") which is damage to interconnects from electrons slamming into metal atoms over and over and slowly ripping apart the wires. Modeling electron migration correctly is really hard, but (from memory) a general relationship is that voltage linearly increases failure rate and temperature exponentially increases it. The constants for these models are determined empirically and, of course, are NDA'd.

In general, I wouldn't worry about it. The MTTF for semiconductors is already very high even under awful temperatures 100+ C, and so as long as you cool it properly you'll be fine.

would it be expected that a non-zero amount would fail?

The failures you describe here are going to be due to setup time violations. These issues shouldn't be transient (assuming identical temperature and voltage) since the performance characteristics of an individual device don't really change over time. Of course, the issues can seem transient as the failures may not actually always cause noticeable corruption (maybe you generate a wrong FPU result but that specific path is only exercised under rare uarch conditions).

So, it's a non-answer, but: yes and no. Maybe your chip is perfectly okay and never has any violations at the parameters you selected. Maybe it does. Neither you (nor in fact the manufacturer, though they do have a better chance since they know the process/design) can ever really be sure--all that's left is empirical burn in testing and hoping for the best :)

magicalhippo3• 2 years ago

I can't find the references right now, but I recall reading that longevity of microcontrollers and similar could also be somewhat accurately modeled by the Arrhenius equation[1], meaning a 10C increase in operating temperature would result in roughly half the expected lifetime.

[1] https://en.wikipedia.org/wiki/Arrhenius_equation

mafuyu• 2 years ago

From what I remember from school, the extremely rough rule of thumb, specifically for thermal effects on the silicon itself, is that +10C will halve the lifespan of the chip. When you try to push a chip with an OC, the power/perf gets highly nonlinear, so you end up making tradeoffs here. Chip vendors like Intel and AMD do a lot of testing and validation to pick power curves that will meet the warranty specs of the chip, but they do have some wiggle room.

There’s a whole bunch of other failure modes that aren’t captured by the 10C rule. It’s more for estimating chip failure due to things like electromigration. You can observe this if you run a desktop CPU overclocked for many years. I had a 2600k that I had to keep bumping the OC down on, and jt eventually bit the dust after a decade.

rodgerd• 2 years ago

I once attended a talk by one of the people at Weta Digital about how they ran their datacentres; they worked out that they could save six figure sums per month by running their aircon lower and blades hotter; HP were prepared to keep the blades in warranty for a three degree bump but no more.

latchkey4• 2 years ago

My experience with running GPUs is that overclocking tends to go with undervolting and it has zero impact on longevity of the chips themselves. Other components like power supplies, with consumable or hand made things, like hand soldered components, are what end up failing.

We had cards in the worst of the worst environments and they ran fine for years on end.

bayindirh3• 2 years ago

I'd not be so sure, actually. Because we have seen other processors on the systems, like RAID or Ethernet cards go "insane" after some years. No overheat, no physical stress, nothing. Normal if a bit too much (HPC) work.

Reboot the system, device just disappears, never to be never seen again. It generally starts after ~6 year mark.

Sometimes device starts to corrupt things silently, but not always. However they too disappear after some time.

Oh, sometimes GPUs do that, too.

kloch• 2 years ago

I remember overclocking the 486DX2-66 in the early 90's. I got the idea after reading my brother's Intel data book and noticed that while the max clock speed was speced at 66 MHz, all of the timing diagrams implied it could run to 80. I borrowed a variable speed clock generator and sure enough it was stable at 80, and started to crash at around 82MHz.

When I started to help friends overclock theirs, I quickly realized the "silicon lottery" variance. Some would only run reliably at 78 or 76 MHz. I bought a bunch of fixed frequency clock generators (that were drop-in replacements for the original on the motherboard) in 2MHz increments due to the variance.

This was back before CPU's had heat sinks or fans, so we quickly figured out that adding those gave better margins. We even made some 10-LED bar temperature display that had a thermocouple glued to the CPU case and indicated 10 degree C increments (green=0-60c, yellow=70-80c, red=90-100c).

winslow• 2 years ago

That sounds like a lot of fun. Do you happen to have any photos of you tinkering especially with the 10-LED bar temp displays?

gorkish2• 2 years ago

I remember overclocking my calculator (TI-85, 1992, Z80 CPU) ... its LO was a 2.7K/22pF RC oscillator which gave it an approximately 2.5MHz clock. To get this type of oscillator to speed up you'd normally lower the capacitance a bit.

The reason that this story is interesting is that in most cases you could just yank C9 entirely and with nothing more than a resistor between the clock pins, you'd get a roughly 300% performance increase. I guess the parasitic capacitance was enough to still oscillate a bit although mostly it would have been random. Looking back, this was basically a CPU being clocked with 50mhz noise and still running happily! Amazing!

lloydatkinson• 2 years ago

Not quite the same but I once was bored enough to keep trying to see how low power a solar powered calculator could work with.

I held my hand over the solar panel at various lengths until the screen cut out and while doing this I just kept hitting random keys and while lifting my hand up.

One day when I did this I must have hit the one in a million chance. It started rapidly counting up by itself!

I think I only got it to happen once more. I suspect the fluctuating voltage and it trying to do calculations while I was pressing keys was just enough to get some gates latched into the wrong state, somehow.

bobim2• 2 years ago

Good memories... I ended up adding a switch under the cells cover because the mod was just draining these way faster. But curve plotting was finally snappy.

epakai• 2 years ago

I have a ST486-DX2-66GS (1998), and I found it is unstable at the stock 66MHz. I actually have to run it at 80MHz to prevent random freezes.

hinkley• 2 years ago

That was before binning really got to be a business model. Of course once a production line was stable, they could generate more high end chips than they actually needed, and so the chip you bought from bin 3 might actually be a bin 2 chip. It always seemed like AMD was really conservative that way, which is why hobbyists loved them.

I have a recollection of a guy who got a 486 DX-33 up to 133 MHz by putting the entire computer in mineral oil and floating chunks of dry ice in it. Watch out for asphyxiation.

t0mas88• 2 years ago

Early GPUs also had this, where you could turn it into a higher end model with just software changes.

smellf• 2 years ago

RK3588-based SBC

Anyone know which SBCs use this chip?

geerlingguy3• 2 years ago

Radxa Rock 5 model B, Turing Pi RK1, Orange Pi 5 (and Plus); there are a few others but those are the models I have purchased and tested. All are more efficient/faster... but also more expensive and less supported. Though RK3599 and 3588 SoCs have both been some of the most widely supported out of Rockchip for Linux applications. They still lack compared to Pi's support though.

mort96• 2 years ago

The NanoPi R6C/R6S as well.

The rk3588 is a nice chip, but support just isn't there yet if you want to do anything with the GPU. The "Panthor" GPU driver, which is the FOSS driver which supports its GPU, was just merged in to Linux and mesa this month[1] (yay!) which means you're probably gonna have to build your own kernel if you want it.

The old mali proprietary driver is borderline unusable on anything remotely modern, only really working on Linux 5.10 and special X11 builds with legacy features re-enabled.

It's crazy that the rk3588 has been on the market for many years at this point and is just now starting to be usable on Linux, but it's exciting that things are taking shape.

[1] https://www.collabora.com/news-and-blog/news-and-events/rele...

lenerdenator• 2 years ago

They still lack compared to Pi's support though.

This should be the central lesson learned from the Raspberry Pi by open-source projects.

There will be faster, there will be smaller, there will be cheaper. But if the user can go on the web and find the _exact_ thing they're looking to do spelled out, they'll buy that product, every time.

rcarmo2• 2 years ago

I have been testing quite a few: https://taoofmac.com/space/blog/2024/02/10/2000

bee_rider• 2 years ago

To achieve that 10% speedup, it ate up about 20% more power, so efficiency-wise, it's not worth it.

There’s a trade off between single threaded performance and power, right? I’d expect the increase in power cost to be between the performance increase squared or cubed. If you expect a one-to-one trade it is never worth it to increase frequency, haha.

The universe will give you throughput at a fair rate, but it is very stingy about latency, in general.

latchkey4• 2 years ago

I ran 150,000 GPUs that were individually tuned for maximum performance.

Silicon lottery, where the chip was on the wafer (edges tend to be less reliable), manufacturing batches, component batches, heat, cooling, power supplies, etc... the list goes on and on...

It is understated how much all of this is a huge impactful thing on performance and stability.

cute_boi• 2 years ago

One thing I don't understand why would people buy raspberry pi instead of mini pc. Mini PC seems to be small, better and more versatile than pi.

cricalix• 2 years ago

You know, he has a video on that too. If you want GPIO, a tiny PC is not the answer (for example).

AnthonBerg• 2 years ago

I need to try one of these USB GPIO thingies. Add GPIO to, well, any computer?

Adafruit FT232H Breakout - General Purpose USB to GPIO, SPI, I2C - USB C & Stemma QT: https://www.adafruit.com/product/2264

Adafruit MCP2221A Breakout - General Purpose USB to GPIO ADC I2C - Stemma QT / Qwiic: https://www.adafruit.com/product/4471

squarefoot• 2 years ago

Mini PCs don't come with GPIOs, which are one of the main reasons that make small SBCs a better choice for some uses. Not a big problem though as there are cheap add on boards bringing GPIO ports to every device. Example: https://www.hardkernel.com/shop/usb-io-board/

The downside is that code becomes slightly more complicated, the upside is that it makes easier to replace the Mini PC with a totally different one, or even emulate it in a VM then connecting the GPIO board using USB pass through.

Rethinking GPIO can also open more possibilities such as putting them beyond a network (say Arduino+ENC28j60 and similar ones for Ethernet, ESP32 for wireless, etc); of course having them outside the main CPU will imply some speed and latency issues, although I'm sure they would remain unnoticed for many non critical use cases.

My question would rather be why the RPi when there are better SBCs out there, but that is my personal taste and the Armbian and DietPi communities being more than enough for me.

Pi 5 overclocking: Silicon Lottery

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