Thursday, September 9th 2021

AMD Zen 4 "Raphael" Processors Feature Improved Thermal Sensors and Power Management

AMD is slowly preparing the launch of the latest and greatest Ryzen processor family based on the Zen 4 CPU core design. Among various things that are getting an overhaul, the Raphael processor generation is now getting revamped temperature reading and better power management circuitry. According to an Igor's Lab report, AMD has prepared a few new improvements that will make temperature reading and power management easier for PC enthusiasts. Currently, the reported CPU temperature is called Tcontrol (Tctl), which is what the cooling solution sees. If Tctl is high, the fans spin up and cool the system. If Tctl is low, the fans slow down to reduce noise.

With Raphael, the CUR_TEMP (current temperature) output part of Tctl has been upgraded to reflect a much smoother curve, and avoid jittering with fans as they are not spiking so suddenly anymore. This is helping contribute to the noise output and has made it run at a consistent fan speed in the system. Another note about Raphael is a new power management technique. AMD has designed the AM5 platform to avoid sudden power spikes, to maintain maximum efficiency over time. It is a design decision made from the very start, and the CPU will try to constrain itself in the TDP range that it is configured for. For more details about the circuitry, please head over to the Igor's Lab article.
Source: Igor's Lab
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18 Comments on AMD Zen 4 "Raphael" Processors Feature Improved Thermal Sensors and Power Management

#1
Richards
Power consumption is gonna be big
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#2
TheLostSwede
RichardsPower consumption is gonna be big
Proof of that?
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#3
londiste
AMD has designed the AM5 platform to avoid sudden power spikes, to maintain maximum efficiency over time. It is a design decision made from the very start, and the CPU will try to constrain itself in the TDP range that it is configured for.
I do not quite see where you get the power spike avoidance. There are VRM and PSU efficiency considerations and checks but nothing really about power spikes. With the way and speed at which these CPUs can vary their frequency, avoiding power spikes is quite difficult.
When it comes to constraining itself - as Igor's story describes, the behaviour is same as Ryzen 3000/5000 where effective power limit is PPT at 1.35x TDP.
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#4
napata
TheLostSwedeProof of that?
Well, we're going from 105W TDP to 170W TDP. That's a 60% increase. PPT for a 170W TDP is 230W. That's a big jump from Zen 3.
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#5
TheLostSwede
napataWell, we're going from 105W TDP to 170W TDP. That's a 60% increase. PPT for a 170W TDP is 230W. That's a big jump from Zen 3.
And we know this will apply to like for like SKUs? Afaik, only the a range of TDP numbers have leaked, not the associated SKUs, so it means nothing so far.
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#6
Richards
Leaks
TheLostSwedeProof of that?
Leaks are saying 170 pl1 now imagine pl2
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#7
HD64G
napataWell, we're going from 105W TDP to 170W TDP. That's a 60% increase. PPT for a 170W TDP is 230W. That's a big jump from Zen 3.
Most possibly the 170W isn't TDP but reap power draw. If so, it isn't such a big increase since the Ryzen 9 CPUs consume ~145W. So, maybe the TDP from 105W will rise to 140W.
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#8
ZoneDymo
RichardsLeaks

Leaks are saying 170 pl1 now imagine pl2
as long as its not Intel level's I guess
Posted on Reply
#9
TheLostSwede
RichardsLeaks

Leaks are saying 170 pl1 now imagine pl2
Again, which SKU/SKUs?
We have leaked spec documents, but it doesn't mean there will be a consumer SKU that uses said specs.
We have ZERO proof of any product so far and we're a year or so away from AM5 product launches, so at this point it's just speculation.
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#10
Gan77
After the last articles by igorslab (thermal pads, evga, capacitor), everyone should have a healthy skepticism)
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#11
eidairaman1
The Exiled Airman
RichardsPower consumption is gonna be big
Baseless opinion.
RichardsLeaks

Leaks are saying 170 pl1 now imagine pl2
What leaks,remember grain of salt , go troll elsewhere
napataWell, we're going from 105W TDP to 170W TDP. That's a 60% increase. PPT for a 170W TDP is 230W. That's a big jump from Zen 3.
Leaks are grain of salt.
Posted on Reply
#12
Darmok N Jalad
I would not be surprised to see AMD leverage higher power usage, since that seems to be the direction we’re going. Intel set the table, and AMD would be foolish to not at least engineer some of their new SKUs to take advantage of that same concept. They are likely preparing for Adler Lake and beyond, and I’d be surprised if we see Intel retreat from their Rocket Lake principles of power management. There’s nothing saying AMD has to use Intel-levels of power, but you know they will if they can AND need to in order to gain a performance lead. As long as they continue to offer performant products at 35W, 65W, and 105W, that is what matters for OEMs, but there’s nothing stopping them from also offering something like a 170W enthusiast product. With Adler Lake, the core wars are really on, so I wouldn’t be surprised to see 24C/48T or 32C/64T consumer-grade Ryzens. With something like that, AMD is going to have to get really creative to have both high core counts and also the highest clock parts.

More to the point of the OP, it’s about time AMD came up with a better way to handle CPU fan speeds. That’s always been a bit of annoyance with Ryzen, IMO. You shouldn’t need to adjust the default fan curve out of the box in order to stop the fan from ramping up and down like it does.
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#13
yotano211
RichardsPower consumption is gonna be big
Intel can say that their's is bigger ;)
Posted on Reply
#14
InVasMani
ZoneDymoas long as its not Intel level's I guess
Nvidia level's are even worse, but granted that's GPU's still something like a R9 290 use to be deemed a power hog and Nvidia seems content with just pushing TDP higher and higher.
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#15
eidairaman1
The Exiled Airman
InVasManiNvidia level's are even worse, but granted that's GPU's still something like a R9 290 use to be deemed a power hog and Nvidia seems content with just pushing TDP higher and higher.
Funny how the R9s are still relevant today...
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#16
TheLostSwede
Actually, thinking about it, maybe, just maybe, the 170W TDP will be for the CPUs with integrated GPU, since that's also rumoured to be a thing.
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#17
gruffi
napataWell, we're going from 105W TDP to 170W TDP. That's a 60% increase. PPT for a 170W TDP is 230W. That's a big jump from Zen 3.
AMD hasn't confirmed any TDPs of Zen 4 yet. All that's floating around are rumors and unproved assumptions. We only know the TDP classes of the AM5 socket. Which go up to 170W, especially designed for liquid cooling solutions. A new segment that doesn't exist on AM4. The "normal" TDP classes end at 120W on AM5. Which isn't a big jump from current 95W. And likely also specified with higher core counts and integrated GPUs in mind. Don't forget, core counts could be increased by at least 50% with smaller nodes. But 120W is only ~25% more than 95W. Which tells us power consumption and efficiency of Zen 4 should be very good. Or what do you expect? Almost twice the power consumption at 10% more performance, to be much worse than Zen 3 efficiency wise? Get a reality check! Zen 4 is a significantly improved architecture, 5nm will add significantly improved transistor efficiency and density. Zen 4 looks like a beast on all fronts. I would be more concerned about Alder Lake. Power numbers look alarming. Again.
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#18
HD64G

[SIZE=2]@[USER=202735]gruffi[/USER] AM4 TDP CPUs go up to 105W[/SIZE]

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