Question DEGRADING Raptor lake CPUs

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Kocicak

Golden Member
Jan 17, 2019
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I noticed some reports about degrading i9 13900K and KF processors.

I experienced this problem myself, when I ran it at 6 GHz, light load (3 threads of Cinebench), at acceptable temperature and non extreme voltage. After only few minutes it crashed, and then it could not run even at stock setting without bumping the voltage a bit.

I was thinking about the cause for this and I believe the problem is, that people do not appreciate, how high these frequencies are and that the real comfortable frequency limit of these CPUs is probably at something like 5500 or 5600 MHz. These CPUs are made on a same process (possibly improved somehow) on which Alder lake CPUs were made. See the frequencies 12900KS runs at. The frequency improvement of the new process tweak may not be so high as some people presume.

Those 13900K CPUs are probably highly binned to be able to find those which contain some cores which can reliably run at 5800 MHz. Some of the 13900K probably have little/no OC reserve left and pushing them will cause them to degrade/break.

The conclusion for me is that the best you can do to your 13900K or 13900KF is to disable the 5800 MHz peak, which will allow you to offset the voltage lower, and then set all core maximal frequency to some comfortable level, I guess the maximum level could be 5600 MHz. With lowered voltage this frequency should be gentler to the processor than running it at original 5500 MHz at higher voltage. You can also run it at lower frequencies, allowing for even higher voltage drop, but then the CPU is slowly loosing its sense (unless you want some high efficiency CPU intended for heavy multithread loads).

Running it with some power consumption limit dependent on your cooling solution to keep the CPU at sensible temperature will help too for sure.
 
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alcoholbob

Diamond Member
May 24, 2005
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What's the best way to underclock / undervolt the cpu? I wouldn't mind giving up 5-10% of performance or even more if it means i'll have a stable NAS / home server appliance. I dont need to squeak out every last bit of performance in my use case.

Undervolting tends to increase performance, not decrease it. Generally doing an adaptive voltage offset while keeping CEP on is a good strategy.
 

Kocicak

Golden Member
Jan 17, 2019
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Are we really comparing HEDT and with a 14900KS?
Why not? Some "gaming service providers" apparently had no problem to use 14900K in their servers.

There is no reason to limit frequency of the workstation CPUs without a real reason, because it limits the performance. If Intel feels they cannot run these CPUs made on the same process using the same cores (?) quicker than at 4800 MHz, they probably have some serious reason for doing so?
 
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cebri1

Senior member
Jun 13, 2019
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Why not? Some "gaming service providers" apparantly had no problem to use 14900K in their servers.

There is no reason to limit frequency of the workstation CPUs without a real reason, because it limits the performance. If Intel feels they cannot run these CPUs made on the same process using the same cores (?) quicker than at 4800 MHz, they probably have some serious reason for doing so?

There is no consumer part with 16 P cores. AMD has an end consumer and HEDT product with the same number and same type of cores and the HEDT product is also clocked lower.

Why? Stability, Thermals, Power Consumption, Not needed for HDET typical workloads, etc.
 

Hulk

Diamond Member
Oct 9, 1999
4,454
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Are these CPUs made on the same process as normal desktop CPUs are?

View attachment 106466

Intel seems to think that for reliable workstation operation these CPUs can run only up to 4,8 GHz. That is 1,4 GHz lower than what 14900KS can run at.

Does anybody have experience with these CPUs, does this 4,8 GHz limit have any significance, or the "real limit" is even lower - 4,6 GHz?

The limit 5400 MHz I set on the new CPU suddenly seems way too high again... It is funny that everything seems to indicate that my "gut feeling" I got years ago that this process is good only up to 5 GHz was correct.
Are you having stability issues at 5.4? I've been fine at 5.5 for over a year.
 

Kocicak

Golden Member
Jan 17, 2019
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Are you having stability issues at 5.4? I've been fine at 5.5 for over a year.
The CPU is brand new, it would not have any problems even at Intel stock breakneck speeds now. I would like to get a few years of completely stable operation out of this CPU, not sure if 5,4 is not too high? I was running the previous 14900K with 5 or 5,2 GHz limit most of the time.
 

Hulk

Diamond Member
Oct 9, 1999
4,454
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The CPU is brand new, it would not have any problems even at Intel stock breakneck speeds now. I would like to get a few years of completely stable operation out of this CPU, not sure if 5,4 is not too high? I was running the previous 14900K with 5 or 5,2 GHz limit most of the time.
I would be more concerned with voltage and heat. I have decided on a manual max voltage of 1.3V, which is about 1.15V under heavy load. Temps are always under 75C with my cooling. I can get 5.5GHz without HT stable in all my apps with that setting. Personally I think anything over 1.3V is too much for long-term operation.
 
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Kocicak

Golden Member
Jan 17, 2019
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Gee, good thing Intel capped voltage at 1.55v . . .
They prolonged the time before failure by a few months by what they did now, I am not sure it is even a half of a year. They are not solving the problem for consumers, they are just minimising the short term damage to the company.
 
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Kocicak

Golden Member
Jan 17, 2019
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I have decided on a manual max voltage of 1.3V ... I can get 5.5GHz
You DO NOT WANT to limit both voltage and frequency!!!

See this example: if I wanted to cap voltage at 1,2, I will set ONLY the frequency limit and I will retain the whole 150mV voltage safety margin for stability (green).



If you decide to limit both voltage at 1,3V and will select frequency at which the CPU is at the moment stable: say 5,6 GHz, you will be left just with a fraction of the original safety voltage margin. And after time as the CPU slowly naturally degrades, the stability voltage increases and reaches your voltage limit and you may start getting instability without really noticing that, as data corruption, etc. You do not want that.
 
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Hulk

Diamond Member
Oct 9, 1999
4,454
2,372
136
You DO NOT WANT to limit both voltage and frequency!!!

See this example: if I wanted to cap voltage at 1,2, I will set ONLY the frequency limit and I will retain the whole 150mV voltage safety margin for stability (green).

View attachment 106516

If you decide to limit both voltage at 1,3V and will select frequency at which the CPU is at the moment stable: say 5,6 GHz, you will be left just with the fraction of the original safety voltage margin. And after time as the CPU slowly naturally degrades, the stability voltage increases and reaches your voltage limit and you may start getting instability without really noticing that, as data corruption, etc. You do not want that.
But in reality the cpu is almost never at the selected voltage because of C states when not under load.
 
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