Looking at the AM5 pinout[0], it looks like those pins are VDDCR and VSS. There might be a little bit of PCIe sprinkled in towards the outer edges, but I'm not 100% on the orientation of this pinout vs the orientation of the CPU. I don't know anything about electricity so I've got nothing else to add.
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 widely used hardware. That's pretty much their whole schtick in recent years.
> Modern CPUs measure their temperature and clock down if they get too hot, don't they?
Yes. It's rather complex now and it involves the motherboard vendor's firmware. When (not if) they get that wrong CPUs burn up. You're going to need some expertise to analyze this.
"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 CPU didn't catch this...
The room temperature or precise way the paste was applied should not matter. Modern CPUs have very advanced dynamic voltage and frequency scaling (DVFS), which accounts for several sensors, including temperature.
These big x86 CPUs in stock configuration can throttle down to speeds where they can function with entirely passive cooling, so even if the cooler was improperly mounted, they'd only throttle.
All that to say, if GMP is causing the CPU to fry itself, something went very wrong, and it is not user error or the room being too hot.
I've heard some really wild noises coming out of my zen4 machine when I've had all cores loaded up with what is best described as "choppy" workloads where we are repeatedly doing something like a parallel.foreach into a single threaded hot path of equal or less duration as fast as possible. I've never had the machine survive this kind of workload for more than 48 hours without some kind of BSOD. I've not actually killed a cpu yet though.
I experienced that with a GPU years ago. A workload I wrote caused a pronounced high frequency noise from the card that I've never encountered the like of before or since. I'd describe it as a very high frequency chirping. I refactored the program rather than seeing what would come of it.
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.
> 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.
Most likely it's the motherboard. ASRock is getting nailed right now for unstable XMP and CPU voltages (it's recommended to undervolt a little just in case).
The Asus Prime B650M motherboards they are using aren't exactly high end.
Enthusiast-oriented motherboards often default enable Precision Boost Overdrive, causing higher power and temperature limits for longer periods. To run the CPU at “stock” you need to go in and disable that. Their default Load Line Calibration might be aggressive as well.
Which motherboards enable PBO out of the box? That’s crazy! I know that motherboard manufacturers set some sketchy default turbo durations for Intel CPUs back when Intel was cagey about the spec and let them get away with it, but I thought that AMD was stricter about such things.
Gradual damage is consistent with over heating. I've seen racks of servers do the same thing.
Overall, there is a continued challenge with CPU temperatures that requires much tighter tolerances both in the thermal solution. The torque specs need to be followed and verified that they were met correctly in manufacturing.
Not that it makes a huge difference since they are supposed to downclock when hot, but what was the actual cooler being used? It doesn't say in the article. My guess is that it's aircooled being only 165W max, but aircooled is not recommended for most newer high end CPUs.
A quick search on the NH-U9S shows it's a compact cooler for small systems, rated for up to 140 W (see e.g. [1]).
The 9950X's TDP (Thermal Design Power) is 170 W, its default socket power is 200 W [2], and with PBO (Precision Boost Overdrive) enabled it's been reported to hit 235 W [3].
I recently built a 9950x3d system and it definitely runs hotter/louder than my other builds. To be fair, it also has a 5090 in it, but I liquid cool the 9950 and over all the system is just hot. If I saw 165W rated on a 170W system, I think that kind of just answers it, I see no reason not to overcool a system with high end electronics on it, and there's no reason to toe the line so closely.
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 170 watts? That's high, but if that's what the motherboards are supposed to be able to deliver, then the pins, socket and pads should have no problem with that.
Where's AMD's testing? Have they learned nothing watching Intel (almost literally) melt down?
I noticed the comments pointing out that TDP is a marketing number, and max power draw for this part can be higher. The cooling seems to have been inadequate.
A rule of thumb I use for cooling is, you can rarely have too much. You should over-engineer that aspect of your systems. That and the power supply.
I have a 7950x, with a water block capable of sinking up to 300W. Under heavy load, I hear the radiator fans spinning up, and I see the cpu temp hover around 90-93 C. That is ok, though cooler would be better. My next build (this one is 2 years old) will also use a water block, but with a higher flow rate, and a better radiator system. I like silent systems, though I don't like the magic smoke being released from components.
I don't know about GMP, but I recently built a PC with 9950X3D. As part of initial testing, I ran Prime95 for 48 hours. Everything ran stable, but I noticed that part of the tests, I think it was FFT or something like that, caused incredibly sharp increase in temp. We are talking 60C average in the rest of the test vs immediate (less than a 5 seconds) 95+ degrees when that FFT thingie started. It was very weird.
That's when I discovered actually ancient term "power virus". Anyway, after talking to different people I dismissed this weird behavior and moved on.
Reading this makes me worry I actually burned mobo in that testing.
All other potential causes aside, including the likely most-relevant of motherboard companies exceeding recommended defaults for power delivery: Running a cooling solution good for less than the TDP (which is NOT the max power, which tends to be about 30% higher than the TDP on these) is frankly extremely dumb. I've seen x950 processors of every generation pull at least double that on extreme workloads. I think it speaks to them being a bit clueless that they did not manually lower the thermal limits. You can cut the power and thermal limits by wild amounts and barely lose 15% multicore performance.
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[ 0.22 ms ] story [ 84.0 ms ] thread[0] https://upload.wikimedia.org/wikipedia/commons/2/2d/Socket_A...
> Modern CPUs measure their temperature and clock down if they get too hot, don't they?
Yes. It's rather complex now and it involves the motherboard vendor's firmware. When (not if) they get that wrong CPUs burn up. You're going to need some expertise to analyze this.
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 CPU didn't catch this...
These big x86 CPUs in stock configuration can throttle down to speeds where they can function with entirely passive cooling, so even if the cooler was improperly mounted, they'd only throttle.
All that to say, if GMP is causing the CPU to fry itself, something went very wrong, and it is not user error or the room being too hot.
I've heard some really wild noises coming out of my zen4 machine when I've had all cores loaded up with what is best described as "choppy" workloads where we are repeatedly doing something like a parallel.foreach into a single threaded hot path of equal or less duration as fast as possible. I've never had the machine survive this kind of workload for more than 48 hours without some kind of BSOD. I've not actually killed a cpu yet though.
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-...
The Asus Prime B650M motherboards they are using aren't exactly high end.
I just wanted to find out what GMP is.
Overall, there is a continued challenge with CPU temperatures that requires much tighter tolerances both in the thermal solution. The torque specs need to be followed and verified that they were met correctly in manufacturing.
The 9950X's TDP (Thermal Design Power) is 170 W, its default socket power is 200 W [2], and with PBO (Precision Boost Overdrive) enabled it's been reported to hit 235 W [3].
[1] https://www.overclockersclub.com/reviews/noctua_nh_u9s_cpu_c...
[2] https://hwbusters.com/cpu/amd-ryzen-9-9950x-cpu-review-perfo...
[3] https://www.tomshardware.com/pc-components/cpus/amd-ryzen-9-...
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 170 watts? That's high, but if that's what the motherboards are supposed to be able to deliver, then the pins, socket and pads should have no problem with that.
Where's AMD's testing? Have they learned nothing watching Intel (almost literally) melt down?
A rule of thumb I use for cooling is, you can rarely have too much. You should over-engineer that aspect of your systems. That and the power supply.
I have a 7950x, with a water block capable of sinking up to 300W. Under heavy load, I hear the radiator fans spinning up, and I see the cpu temp hover around 90-93 C. That is ok, though cooler would be better. My next build (this one is 2 years old) will also use a water block, but with a higher flow rate, and a better radiator system. I like silent systems, though I don't like the magic smoke being released from components.
That's when I discovered actually ancient term "power virus". Anyway, after talking to different people I dismissed this weird behavior and moved on.
Reading this makes me worry I actually burned mobo in that testing.