GMP damaging Zen 5 CPUs?

> [...] a bunch of dramatic YouTube content [...]

That framing doesn't do him and the team justice. There is (or better, was) a 3.5h long story about NVIDIA GPUs finding their ways illegaly from the US to China, which got taken down by a malicious DMCA claim from Bloomberg. It is quite interesting to watch (Can be found archive.org).

GN is one of the last pro-consumer outlets, that keep on digging and shaking the tree big companys are sitting on.

The small coolers used by them are not recommended by Noctua for 9950X. Noctua recommends only bigger coolers for 9950X, which dissipates 200 W permanently on a workload like theirs (which is much less than the over 250 W dissipated in similar conditions by the competing Intel CPUs).

Despite this, the overtemperature protection of the CPUs should have protected the CPUs and prevent any kind of damage like this.

Besides the system that varies continuously the clock frequency to keep the CPU within the current and power consumption limits, there is a second protection that stops temporarily the clock when a temperature threshold is exceeded. However, the internal temperature sensors of the CPUs are not accurate, so the over-temperature protection may begin to act only at a temperature that is already too high.

So these failures appear to have been caused by a combination of not using the appropriate coolers for a 200 W CPU, combined with the fact that AMD advertises a 200-W CPU as an 170-W CPU, fooling naive customers into believing that smaller coolers are acceptable, and with either some kind of malfunction of the over-temperature protection in these CPUs or with a degradation problem that happens even within the nominal temperature range, but at its upper end.

Wendell at Level1Techs often goes more in-depth on the software testing and datacenter use-case analysis through partnerships with friends who run lots of machines in datacenters.

GN is unique in paying for silicon-level analysis of failures.

der8auer also contributes a lot to these stories.

I tend to wait for all 3 of their analyses, because each adds a different "hard-won" perspective.

He's a bit sensationalist, yes, but I am thankful that he saved us from buying affected Intel CPUs.

AMD has failed to be reliable with its Zen 4 and Zen 5 consumer CPUs, just at the same time Intel did the same with their 13k and 14k higher end CPUs.

AMD is somewhat worse than Intel as their DDR5 memory bus is very "twitchy" making it hard to get the highest DDR5 timings, especially with multiple DIMMs per channel.

All you really need to see is the picture of the CPU with thermal paste only on one half. Thermal throttling is tuned to work when there is 1. a sufficient heatsink (theirs was significantly below requirements) and 2. it is installed correctly so that its triggers for downclocking happen with the correct timing. This is just another instance of ridiculous PEBCAK error

They don't say what temperature the CPU was reporting which seems like an odd omission. Whatever the specs of your cooler etc check the temperature it's actually running at. Go by what the CPU is saying! I've got the older 3950x, and the first one died after a few months (still in warranty) with a cooler in spec, but it would go into the 90s at full load just doing big builds. I replaced the heatsink with a basic watercooler when the replacement chip arrived and it's running at least 20c cooler at full load.

When I see the term TDP, I remember what I have read in the "Thermal Design Document" of Intel Core2Quad Q6600 and the family it belongs:

> The thermal solution bundled with the CPUs is not designed to handle the thermal output when all the cores are utilized 100%. For that kind of load, a different thermal solution is strongly recommended (paraphrased).

I never used the stock cooler bundled with the processor, but what kind of dark joke is this?

You are correct. In fact these guys measured a maximum socket power consumption of 240 watt using a 9950X at stock settings, running prime95. So far above the "170 watt" TDP:

https://hwbusters.com/cpu/amd-ryzen-9-9950x-cpu-review-perfo...

I have a 65W TDP CPU, and the difference in power draw (measured at the outlet) from idle to full CPU load is over 100W; it seems to just raise the clock until it hist 95C, so if I limit the CPU fan's top speed, the power draw goes down.

Wow, I can't believe how BS this TDP is! I feel like a total idiot! I've always assumed it's sorta-kinda a tight upper bound on power consumption, perhaps with some allowance for "imperfections" in the dissipation properties of the CPU, and that I shouldn't sweat the details.

Couldn't this count as false/misleading advertizing though?

This was my first question as well- I thought it had been a long, long time since you could fry a CPU by taking away the heatsink.

As in... what, AMD K6 / early Pentium 4 days was the last time I remember hearing about cpu cooler failing and frying a cpu?

Yes, this is the point - software should never be able to physically damage the hardware it is on.

If it can, then the hardware is to blame.

If the throttling is not stable it could increase stress on the part by creating a bunch of transient but large thermal cycles through the chip. It would need to have some kind of exponential backoff on throttle so it doesn't immediately try to raise the frequencies when the temperature slightly dips.

I would be interested to see if they had the same result with PTM7950 thermal material instead of paste. I've seen significantly better temps with these modern phase-change compounds, and they essentially eliminate application errors.

Noctua does not use TDP for their heatsinks and instead have CPU compatibility charts. They say it's fine, with "medium turbo/overclocking headroom". https://ncc.noctua.at/cpus/model/AMD-Ryzen-9-9950X-1831

That’s a good catch, but don’t modern CPUs thermally throttle, rather than risk damage? Not that you should rely on this with an underpowered cooling solution but I would expect worse performance, not a fried chip.

Yikes, this is the cheapest motherboard and failed Hardware Unboxed VRM tests. https://youtu.be/DTFUa60ozKY?t=744

My friend just had an ASRock board cook his AMD CPU. Apparently a very common problem.

Can you link to a reputable source for what settings I should use on my asrock motherboard? I'd like to avoid this.

And the close-up photos of the socket with pins are missing.

This is a nice guess but the likelihood that actual silicon area is closely connected to the pins in that area is not so obvious

Different use patterns will result in different temperatures. Very tight math loops (no memory/IO wait) will lead to higher temperatures than something that that relies on L2/3 cache or main memory, even though they’ll both report “100% CPU use” and probably use similar amounts of power. And, different operations will produce heat in different areas of the die; depending on physical layout, some operations might generate heat in a tiny cluster, whereas some others might generate heat in larger spread out areas. Even though both of those cases might use the same amount of power and generate the same amount of heat, the temperatures will be drastically different due to the heat concentration.

Iirc the FFT step uses AVX, and on Zen 5 that’ll be AVX-512. It should keep 100% of the required data in L1 caches, so you’re keeping the AVX units busy literally 100% of the time if things are working right. The rest of the core will be cold/inactive, so if you’re dumping an entire core’s worth of power into a teeny tiny ALU, which is gonna result in high temps. Most (all?) processors downclock under heavy AVX load, sometimes by as much a 1GHz (compared to max boost), because a) the crazy high temperatures results in more instability at higher frequencies, and b) if the clocks were kept high, temperatures would get even higher.

Try LINPACK, it's even more stressful than Prime95.

I've never had the machine survive this kind of workload for more than 48 hours without some kind of BSOD.

Then you shouldn't trust the results of your work either, as that's indicative of a CPU that's producing incorrect results. I suggest lowering the frequency or even undervolting if necessary until you get a stable system.

...and yes, wildly fluctuating power consumption is even more challenging than steady-state high power, since the VRMs have to react precisely and not overshoot or undershoot, or even worse, hit a resonance point. LINPACK, one of the most demanding stress tests and benchmarks, is known for causing crashes on unstable systems not when it starts each round, but when it stops.

Is that, like, an intentional stress-test for the hardware that you’ve come up with?

> But doesn't the hardware "overclock" and "overvolt" automatically these days?

If it's done by the manufacturer it's within spec of course. As designed.

The overclock game was all about running stuff out of spec and getting more performance out of it than it was supposed to create.

Also "play other teen games" should not damage your cpu.

I'm guessing the temperature could increase quite fast (milliseconds or less) in heavy duty areas, especially when going scalar-to-dense-vector operations.

My best understanding of the avx-512 'power license' debacle on Intel CPUs was that the processor was actually watching the instruction stream and computing heuristics to lower core frequency before reaching avx512 or dense-avx2 instructions. I guessed they knew or worried that even a short large-vector stint would fry stuff...

Apparently voltage and thermal sensor have vastly improved and looking at the crazy swings on NVIDIA GPU's clocks seem to agree with this :-)

They said it took months for each CPU to fail. Both systems used the same inadequate heatsink/fan. Then there's also the lower-end motherboards (they are not "top-quality", the brand means nothing) and the miniscule 450W power supply used in the initial configuration, which are confusingly paired with a 16-core CPU and 64/96GB of RAM.

It doesn't strike me as odd that running an extremely power-heavy load for months continuously on such configurations eventually failed.

Are we talking "slowly" in a relative sense? A silicon die of this size has a thermal mass (guessing) around 10⁻³ J/K but a power dissipation rate over 200W, so it can rise from room temperature to junction temperature limits almost instantly.