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GMP damaging Zen 5 CPUs?

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Re: GMP damaging Zen 5 CPUs?

#51

Post by kllrnohj »

einpoklum wrote: post #44
db48x wrote: post #19

> The so-called TDP of the Ryzen 9950X is 170W. The used heat sinks are specified to dissipate 165W, so that seems tight. TDP numbers are completely made up. They don’t correspond to watts of heat, or of anything at all! They’re just a marketing number. You can't use them to choose the right cooling system at all. https://gamersnexus.net/guides/3525-amd-ryzen-tdp-explained-...

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?

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

For what, exactly? TDP stands for "thermal design power" - nothing in that means peak power or most power. It stopped being meaningful when CPUs learned to vary clock speeds and turbo boost - what is the thermal design target at that point, exactly? Sustained power virus load?

Re: GMP damaging Zen 5 CPUs?

#52

Post by jsheard »

pharrington wrote: post #45
tw04 wrote: post #10

That looks like a combination of improperly mounting the heatsink and noctuna being wrong in their recommendation to offset it. I’d imagine for gaming cooling one side more makes sense but my completely uneducated guess is that GMP is working a different part of the CPU than gaming does.

I'd assume both GMP and any CPU intensive game just prefer the performance cores.

AMDs desktop chips don't have distinct P and E cores, they're all P cores. AMD do have an E core design but it's currently only used in mobile and server parts.

Re: GMP damaging Zen 5 CPUs?

#53

Post by toast0 »

fithisux wrote: post #20

[flagged]

> The x86-64 ISA is a POS BTW.

> It needs major refactoring. The backwards compatibility is killing the platform.

People have been saying that for 30 years at this point. You can dislike the ISA all you want, but the platform doesn't seem to be dieing all that fast, and compatibility helps it live. Compatibility is how you sell chips: windows on arm doesn't sell because people are concerned about running their apps; android on x86 didn't sell well in part because many apps with native code didn't include x86 binaries; mac os on arm sells because Apple made things work and pushes hard.

A better ISA doesn't prevent chips from burning up. Apple's chips don't burn up because they stay away from high clocks and high power, which is easy when they force vertical integration.

Re: GMP damaging Zen 5 CPUs?

#54

Post by db48x »

gruez wrote: post #50
einpoklum wrote: post #44

Earlier quoted context omitted.

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?

It's thermal design power, ie. it's the power that it's designed for, not absolute max.

No, they don’t design the chip with these numbers in mind. The marketing department picks the number they want based on how they want customers to think about the chip, and which competitors they want you to compare it against. They just plug in whatever numbers are needed into the formula so that the number comes out how they want it.

Re: GMP damaging Zen 5 CPUs?

#55

Post by nerdsniper »

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…

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.

Re: GMP damaging Zen 5 CPUs?

#56

Post by gruez »

db48x wrote: post #54
gruez wrote: post #50

Earlier quoted context omitted.

It's thermal design power, ie. it's the power that it's designed for, not absolute max.

No, they don’t design the chip with these numbers in mind. The marketing department picks the number they want based on how they want customers to think about the chip, and which competitors they want you to compare it against. They just plug in whatever numbers are needed into the formula so that the number comes out how they want it.

>The marketing department picks the number they want based on how they want customers to think about the chip, and which competitors they want you to compare it against. They just plug in whatever numbers are needed into the formula so that the number comes out how they want it.

Are you just describing product segmentation? ie. how the ryzen 5700x and 5800x are basically the same chip, down to the number of enabled cores, except for clocks and power limit ("TDP")?

Re: GMP damaging Zen 5 CPUs?

#57

Post by touisteur »

fxtentacle wrote: post #6

"We suspect that GMP's extremely tight loops around MULX make the Zen 5 cores use much more power than specified, making cooling solutions inadequate." I feel like if this was heat related, the overall CPU temperature should still somewhat slowly creep up, thereby giving everything enough time for thermal throttling. But their discoloration sure looks like a thermal issue, so I wonder why the safety features of the C…

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 :-)

Re: GMP damaging Zen 5 CPUs?

#60

Post by wahern »

db48x wrote: post #54
gruez wrote: post #50

Earlier quoted context omitted.

It's thermal design power, ie. it's the power that it's designed for, not absolute max.

No, they don’t design the chip with these numbers in mind. The marketing department picks the number they want based on how they want customers to think about the chip, and which competitors they want you to compare it against. They just plug in whatever numbers are needed into the formula so that the number comes out how they want it.

That seems a little too cynical. It matters how a customer might use a chip, such as the type of cooling that would be expected in a typical system using that model, and that's informed by the advertised specifications. Base clocks and the amount of SRAM also figure into TDP. No doubt there are completely arbitrary aspects to TDP driven purely by profit-focused market segmentation, but it's not just that.

That said, it's definitely very frustrating as someone who does the occasional server build. Not only does TDP not reflect minimum or maximum power draw for a CPU package itself, but it's also completely divorced from power draw for the chipset(s), NICs, BMCs (ugh), etc, not to mention how the vendor BIOS/firmware throttles everything, and so TDP can be wildly different from power draw at the outlet. The past 5 years have kind of sucked for homelab builders. The Xeon E3 years were probably peak CPU and full-system power efficiency when accounting for long idle times. Can you get there with modern AMD and Intel chips? Maybe. Depends on who you ask and when. Even with identical CPUs, differences in motherboard vendor, BIOS settings, and even kernel can result in drastically different (as in 2-3x) reported idle power draw.

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