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GMP damaging Zen 5 CPUs?

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Re: GMP damaging Zen 5 CPUs?

#141

Post by adrian_b »

topspin wrote: post #4

As there is ongoing drama with Zen 5 and power issues, there are people with the instruments and the motivation to investigate this. You should consider contacting Gamers Nexus, and help them to get your test suite running. They can measure power draw and do a thermal analysis of this CPU, and they'd likely be eager to do it, given the possibility of making a bunch of dramatic YouTube content about design flaws in wi…

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.

Re: GMP damaging Zen 5 CPUs?

#142

Post by marshray »

dcrazy wrote: post #130
mrb wrote: post #92

Earlier quoted context omitted.

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 don’t understand this argument. If the CPU dissipated an equal number of watts of heat energy as it consumed from the wall, there wouldn’t be any energy left to do actual useful work. Isn’t the extra 100W accounted for by things like changing the state of flip-flops? In other words, mustn’t one consider the entropy reduction of the system as an energy sink?

Clocking and changing register states requires charging and discharging the gate capacitance of a bunch of MOSFET transistors. The current that results from moving all that charge around encounters resistance, which converts it to heat. Silicon is only a "semi" conductor after all.

You are correct that there is energy bound in the information stored in the chip. But last I checked, our most efficient chips (e.g., using reversible computing to avoid wasting that energy) are still orders of magnitude less efficient than those theoretical limits.

Re: GMP damaging Zen 5 CPUs?

#143

Post by rurban »

The /r/asrock reddit is full of such stories. In my case I've burned two server motherboards with those watercooled 9950X chips. The CPU is still fine though. It's happening with all H100's on 100%. Too much power draw we assume.

Re: GMP damaging Zen 5 CPUs?

#144

Post by marshray »

lightedman wrote: post #131
nisegami wrote: post #24

Earlier quoted context omitted.

I initially scoffed at the 150-200 amps. But I know core voltage is usually in the neighbourhood of 1V so to draw 200W, you really would have to basically be moving 200A of current. That's wild.

And you're pushing that many amps across a piece of silicon roughly the size of your thumbnail all said and done.

A spot welder, basically.

Re: GMP damaging Zen 5 CPUs?

#145

Post by wkat4242 »

> Did the CPUs die of heat stroke? Modern CPUs measure their temperature and clock down if they get too hot, don't they?

They do, but the thermal sensors are spread out a bit. It could be that there's a sudden spot heating happening that's not noticed by one of the sensors in time.

Re: GMP damaging Zen 5 CPUs?

#146

Post by wkat4242 »

trebligdivad wrote: post #74
topspin wrote: post #4

As there is ongoing drama with Zen 5 and power issues, there are people with the instruments and the motivation to investigate this. You should consider contacting Gamers Nexus, and help them to get your test suite running. They can measure power draw and do a thermal analysis of this CPU, and they'd likely be eager to do it, given the possibility of making a bunch of dramatic YouTube content about design flaws in wi…

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 wat…

Maybe they didn't have anything logging the temperature. They didn't expect it to die after all.

Re: GMP damaging Zen 5 CPUs?

#147

Post by wkat4242 »

userbinator wrote: post #119

We don't overclock or overvolt or play other teen games with our hardware. But doesn't the hardware "overclock" and "overvolt" automatically these days? This reminds me of the Intel CPUs with similar problems a year ago, and AFAIK it was caused by excessive voltage: https://news.ycombinator.com/item?id=41039708

> 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.

Re: GMP damaging Zen 5 CPUs?

#148

Post by wkat4242 »

mrheosuper wrote: post #120
userbinator wrote: post #119

We don't overclock or overvolt or play other teen games with our hardware. But doesn't the hardware "overclock" and "overvolt" automatically these days? This reminds me of the Intel CPUs with similar problems a year ago, and AFAIK it was caused by excessive voltage: https://news.ycombinator.com/item?id=41039708

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

Ehh I've seen some of these teen games involve complete immersion in oil or even water (can be done as distilled water doesn't conduct but if only a pinch of salt gets into it...). Or even more extreme things like liquid nitrogen. This can have all sorts of weird effects on CPUs not designed for that kinda stuff (e.g. thermal contraction to temperatures under low load way below spec, or cracking due to extreme thermal gradients).

Re: GMP damaging Zen 5 CPUs?

#149

Post by wkat4242 »

chaoskitty wrote: post #105

This isn't good. Then again, the amount of power going in to these CPUs is way too high. Take the AlphaServer DS25. It has wires going from the power supply harness to the motherboard that are thick enough to jump a car. The traces on the motherboard are so thick that pictures of the light reflecting off of them are nothing like a modern motherboard. The two CPUs take 64 watts each. Now we have AMD CPUs that can take…

> Take the AlphaServer DS25. It has wires going from the power supply harness to the motherboard that are thick enough to jump a car. The traces on the motherboard are so thick that pictures of the light reflecting off of them are nothing like a modern motherboard. The two CPUs take 64 watts each.

I am not involved in power VRM for modern moderboards. But I can imagine they are some some smart stuff like compensating for transport losses by increasing the voltage somewhat at the VRM so the designed voltage still outputs at the CPU. Of course this will cause some heating in the motherboard but it's probably easily controlled.

In the day of the alpha that kind of thing would have been science fiction so they had no alternative but to minimise losses. You can't use a static overvoltage because then when the load drops the voltage coming out will be too high (transport loss depends on current).

Also, in those days copper cost a fraction of what it costs now so with any problem just doing 'moah copper' was an easy solution. Especially on server hardware like the Alpha with big markup.

And server hardware is always overengineered of course. Precisely to prevent long-term load problems like this.

Re: GMP damaging Zen 5 CPUs?

#150

Post by MadnessASAP »

dcrazy wrote: post #130
mrb wrote: post #92

Earlier quoted context omitted.

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 don’t understand this argument. If the CPU dissipated an equal number of watts of heat energy as it consumed from the wall, there wouldn’t be any energy left to do actual useful work. Isn’t the extra 100W accounted for by things like changing the state of flip-flops? In other words, mustn’t one consider the entropy reduction of the system as an energy sink?

I think the numbers are more like 239W lost to heat. Information and the transformation of it does have some inherent energy cost. But it is very, very small. And you end up getting that back as heat somewhere else down the line anyways.
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