That's wild. My 9950X died for some reason, never overclocked.
GMP damaging Zen 5 CPUs?
191–200 of 240 posts
Re: GMP damaging Zen 5 CPUs?
#192Earlier quoted context omitted.
No, the TDP number doesn’t even vaguely approximate anything. You can’t use the number to predict anything, or to plan, or to estimate your electric bill, or anything like that.
Isn't TDP supposed to be an upper bound of how much power budget there is for a chip when it's running under maximum IPC (which implies AVX512 workload spread across all cores with all the test data in all the L1 caches)? I guess that power budget can vary due to process imperfections and/or CPU bugs but saying that it doesn't approximate anything is hard to believe. How about the PSU then, e.g. is 800W PSU a made-up…
No, TDP is only supposed to be a marketing number. It would be nice if it were a real number that meant something, but CPU manufacturers don’t want to include really complicated information in their marketing. When they want to emphasize that a processor is powerful, they increase the TDP number! When they want you to buy an efficient laptop, they just lower the number! Same cpu, same number of transistors, same number of cores and PCIe lanes, different model number, different TDP number.
The power ratings of power supplies, on the other hand, are perfectly valid. Try to draw more than that and they will blow a fuse. Note however that a power supply’s efficiency is nonlinear. If your computer is really drawing 800W from the power supply, then the power supply is probably drawing 1000W from the wall, or maybe more. The difference is converted into heat during the conversion from 120V AC to 12V DC (and 5V DC and 3.3V DC, etc, etc). That’s an efficiency of 80%. But if your PC was drawing 400W from the same power supply then maybe the efficiency would be 92% instead, and the supply would only draw 435W from the wall. The right power supply for your computer is the cheapest one that is most efficient at the level of power that your computer actually needs. The Bronze/Gold/Platinum efficiency ratings are almost BS made–up marketing things though, because all that tells you is that it hits a certain efficiency rating at _some_ power level, not that it does so at the power level you’ll typically run your computer at.
There is a similar but more extreme set of nonlinearities when talking about the power drawn by a CPU (or a GPU). The CPU monitors its own temperature and then raises or lowers its own frequency multiplier in response to those temperature changes. This means that the same CPU will draw more power and run faster when you cool it better, and will run more slowly and generate less heat when the ambient temperature is too high. There are also timers involved. Because so many of the tasks we actually give to our CPUs are bursty, CPU performance is also bursty. The CPU will run at a high speed for a short period of time, then automatically scale back after a few seconds. The exact length of that timer can be adjusted by the BIOS, so laptop motherboards turn the timer down really short (because cooling in a laptop is terrible), while gamer motherboards turn them way up (because gamers buy overbuilt Noctua coolers, or water cooling, or whatever). Intel and AMD cannot even tell you a single number that encompasses all of these factors. Thus TDP became entirely meaningless and subject to the whims of marketing.
Re: GMP damaging Zen 5 CPUs?
#193The 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 sa…
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?
K6 depended on motherboard having thermal sensors - and which had to properly attach to the CPU in the first place.
Built-in thermal sensing came later.
Re: GMP damaging Zen 5 CPUs?
#194Earlier quoted context omitted.
No, clock speed and cache have nothing to do with TDP. AMD uses a simple formula to calculate TDP. It is the temperature of the IHS minus the air temperature measured at the cpu cooler’s intake fan, divided by a conversion faction in °C/W. But they don’t use real temperatures from real systems. They just make up a different set of temperatures for each CPU that they sell, so that the TDP comes out to the number that…
> The formula doesn’t even mean anything, in real physical terms. From your description the formula is how you would calculate the power for which a certain heatsink at a given ambient temperature would result in the specified IHS temperature. The °C/W number is not a conversion factor but the thermal resistance[1] of the heatsink & paste, that is a physical property. So unless I misunderstood you it's very much some…
It might be a useful formula _if_ the numbers were real. Note that when AMD tells you that a 9900X cpu is has a 120W TDP, that's because they picked three numbers to plug into that formula that result in 120 popping out. They picked the result of 120 first, and then found numbers to put into the formula so that it gives you that result.
But the reason I say that it’s physically meaningless is that real heat dissipation is strongly temperature dependent. The thermal conductivity of a heatsink goes up as the temperature goes up because heat is more effectively transferred into the air at higher temperatures.
Re: GMP damaging Zen 5 CPUs?
#195Earlier quoted context omitted.
This is per design. On AM5 processors, there's a hotspot on the lower half of the processor where the dies that contain the CPU cores are located. Noctua recommends that AM5 users mount their coolers shifted towards the lower side of the processor for optimal cooling performance, see https://noctua.at/en/offset-am5-mounting-technical-backgroun... . You may have missed the paragraph in the article that explicitly poin…
While it is noctua advice, I don't think AMD supports that view, so it would seem correct to at least test the cpu the way the vendor recommends before making conclusions
You may have missed the part in the article that says that they only switched to offset mounting after their first Ryzen 9950X died when the cooler was mounted centered.
> But note that the 1st failure happened with a more centred heat sink. We only made the off-centre mounting for the 2nd system as to minimise the risk of a repeated system failure.
Re: GMP damaging Zen 5 CPUs?
#196> 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-...
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 w…
This is more how I think too: using a cooler that supports your CPU TDP is generally fine because most people will not run a CPU 100% for an extended amount of time. But in this case they seem to be running the CPU 100% for an extended amount of time AND are using an under-spec'ed cooler (even if it is just by 5W).
You don't even need to change the actual cooler since for AMD CPUs you can pretty much customize the TDP whatever way you want, and by default they run well above their efficiency curve. For example, my 7600X has a default TDP of 105W but I run it in Eco Mode (65W) with undervolt and I barely lose any performance. Even if I did no undervolt, running the CPU in Eco Mode is generally preferable since the performance loss is still negligible (~5%).
Re: GMP damaging Zen 5 CPUs?
#197When I worked at Linden Lab we had a deal going with IBM. Either as part of that deal or in an attempt to impress our larger partner, many of us got Thinkpads. I actually kind of like them, since the cost wasn't coming out of my budget.
Inside Linden, about 90% of meetings were held in-world, so we constantly had the Second Life viewer up. About three months later our Thinkpads started failing. Apparently they thought people who would a) buy a thinkpad and b) use it to play video games wouldn't be playing video games 12 hours per day (though as many have pointed out, does one "play" Second Life? especially if you're using it for work.)
After 3 months of use, the Second Life client had caused sufficient heating cycles so as to delaminate the PCB under the GPU.
I'm sort of proud of this. Our software was dangerous.
Re: GMP damaging Zen 5 CPUs?
#198Earlier quoted context omitted.
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 w…
This is more how I think too: using a cooler that supports your CPU TDP is generally fine because most people will not run a CPU 100% for an extended amount of time. But in this case they seem to be running the CPU 100% for an extended amount of time AND are using an under-spec'ed cooler (even if it is just by 5W). You don't even need to change the actual cooler since for AMD CPUs you can pretty much customize the TD…
For a general purpose system, this line of thinking makes sense. However, the desktop system in question was built to be daily driven and support some high performance code research, so it had to endure some serious loads for a desktop computer.
I went the other way and overspecced the CPU cooler and added some silent but high CFM capable fans on the system. The motherboard I got was able to adjust all fans depending on the system temps, so it scaled from a very silent desktop to a low-key space heater automatically under load.
Instead of undervolting the processor, I was using a tweaked on-demand governor on the system which stuck to lower power levels more than usual, so unless I was doing software development and testing things, it stayed cool and silent.
BTW, by 100%, I'm talking about completely saturating the CPU pipeline. Not pseudo 100% where CPU reports saturation but most of the load is iowait.
Re: GMP damaging Zen 5 CPUs?
#199Earlier 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?
> 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?
> For what, exactly? TDP stands for "thermal design power"
The chip is not designed for this rate of power dissipation; and it is not the rate of power dissipation that you can expect to get from the chip.
Re: GMP damaging Zen 5 CPUs?
#200i think that if the cpu tdp is 170W and your cooling solution is rated for 165W and both cpu broke under sustained full load you replied yourself.
Plus i don't see how reducing the contact ara with the skewed mounting can benefit in any way the heat transfer