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onlysublime
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AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 1:43 pm

Okay, so I have my Ryzen 1800X fully up, armed, and operational.

And in the BIOS, the CPU temp is reading as 60C? Is this the normal temp? I read that AMD says we're supposed to take 20C off the reading to get the true reading?

I have the Noctua NH-D15 SE-AM4 CPU cooler, Gigabyte GA-AX370 Gaming K7 motherboard, and running 16 GB RAM at 3200. The case is the Corsair 760T. I have not had a chance to install the beta BIOS release from Gigabyte (still running original firmware), but having the hardest time updating the beta firmware (keeps failing).
 
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 1:56 pm

The story is that apparently the "X" series (but apparently not the R1700 non-X model) RyZen parts intentionally over-report their core temperature by 20C.
This is apparently because they want to trick the fan controllers into throttling up the fans earlier or something and that's good for cooling... apparently.

Frankly I think having monitoring hardware that's intentionally designed to deliver false information is not a good strategy (and for some reason it's not required on Intel parts or even some RyZen parts) but that's just me.
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Vhalidictes
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 2:04 pm

The only thing I can think of is that AMD wants the 1800X to get better cooling, in order to auto-OC higher.

This is a crummy way of doing that though.
 
Froz
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 2:13 pm

I couldn't believe they would do something like that, but here it is, on their website:

https://community.amd.com/community/gam ... ity-update

Temperature Reporting

The primary temperature reporting sensor of the AMD Ryzen™ processor is a sensor called “T Control,” or tCTL for short. The tCTL sensor is derived from the junction (Tj) temperature—the interface point between the die and heatspreader—but it may be offset on certain CPU models so that all models on the AM4 Platform have the same maximum tCTL value. This approach ensures that all AMD Ryzen™ processors have a consistent fan policy.

Specifically, the AMD Ryzen™ 7 1700X and 1800X carry a +20°C offset between the tCTL° (reported) temperature and the actual Tj° temperature. In the short term, users of the AMD Ryzen™ 1700X and 1800X can simply subtract 20°C to determine the true junction temperature of their processor. No arithmetic is required for the Ryzen 7 1700. Long term, we expect temperature monitoring software to better understand our tCTL offsets to report the junction temperature automatically.


I'm not sure if I understand them - do they really say that non-X CPUs are supposed to be 20 degrees warmer (and have 20 degrees higher maximum tCTL value)?

Nevertheless, 40 degrees at idle sounds like much to me. I would check the heatsink and the paste.
 
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 3:00 pm

In all likelihood, the sensors in the CPU aren't reporting an actual number back to the motherboard, so and if the stories about there being such a lack of communication are true I can see how that could make things difficult in trying to report accurate temperatures. The +20C offset would be there to spin up the fans before the fire and death could happen. If that were the case, then the 1700 should behave the same way, and apparently it doesn't, so it's just totally weird.
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 3:08 pm

Froz wrote:
I couldn't believe they would do something like that, but here it is, on their website:

https://community.amd.com/community/gam ... ity-update

Temperature Reporting

The primary temperature reporting sensor of the AMD Ryzen™ processor is a sensor called “T Control,” or tCTL for short. The tCTL sensor is derived from the junction (Tj) temperature—the interface point between the die and heatspreader—but it may be offset on certain CPU models so that all models on the AM4 Platform have the same maximum tCTL value. This approach ensures that all AMD Ryzen™ processors have a consistent fan policy.

Specifically, the AMD Ryzen™ 7 1700X and 1800X carry a +20°C offset between the tCTL° (reported) temperature and the actual Tj° temperature. In the short term, users of the AMD Ryzen™ 1700X and 1800X can simply subtract 20°C to determine the true junction temperature of their processor. No arithmetic is required for the Ryzen 7 1700. Long term, we expect temperature monitoring software to better understand our tCTL offsets to report the junction temperature automatically.


I'm not sure if I understand them - do they really say that non-X CPUs are supposed to be 20 degrees warmer (and have 20 degrees higher maximum tCTL value)?

Nevertheless, 40 degrees at idle sounds like much to me. I would check the heatsink and the paste.


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onlysublime
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 4:22 pm

Froz wrote:
I couldn't believe they would do something like that, but here it is, on their website:

https://community.amd.com/community/gam ... ity-update

Temperature Reporting

The primary temperature reporting sensor of the AMD Ryzen™ processor is a sensor called “T Control,” or tCTL for short. The tCTL sensor is derived from the junction (Tj) temperature—the interface point between the die and heatspreader—but it may be offset on certain CPU models so that all models on the AM4 Platform have the same maximum tCTL value. This approach ensures that all AMD Ryzen™ processors have a consistent fan policy.

Specifically, the AMD Ryzen™ 7 1700X and 1800X carry a +20°C offset between the tCTL° (reported) temperature and the actual Tj° temperature. In the short term, users of the AMD Ryzen™ 1700X and 1800X can simply subtract 20°C to determine the true junction temperature of their processor. No arithmetic is required for the Ryzen 7 1700. Long term, we expect temperature monitoring software to better understand our tCTL offsets to report the junction temperature automatically.


I'm not sure if I understand them - do they really say that non-X CPUs are supposed to be 20 degrees warmer (and have 20 degrees higher maximum tCTL value)?

Nevertheless, 40 degrees at idle sounds like much to me. I would check the heatsink and the paste.


So does anyone know what the temps should be for the 1800X in the BIOS (will do a reading in Windows soon which I haven't done yet as I just finished the system build not long ago). 40C is too high for this processor?
 
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 5:21 pm

Redocbew wrote:
In all likelihood, the sensors in the CPU aren't reporting an actual number back to the motherboard, so and if the stories about there being such a lack of communication are true I can see how that could make things difficult in trying to report accurate temperatures. The +20C offset would be there to spin up the fans before the fire and death could happen. If that were the case, then the 1700 should behave the same way, and apparently it doesn't, so it's just totally weird.


They're the same core. Since the offset is different, I assume that this is a backdoor attempt to make the X processors run cooler == faster. If anyone else has another idea I'd like to hear it.
 
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 5:33 pm

I remember reading somewhere the max stable temp was 105c in AMD temps, so about 85c. With MX-4 paste and this cooler, my wife's stock clocked 1700x will hit 93c (or real 73c) after running prime95 for 15 min.

I almost choked when I saw the temps jump to 90c. Checked the heatsink, checked everything over and all was right. There was even warm air coming from the cooler. AMD just added a +20c to the temps. So at idle of 50c, that is actually 30c.
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Fri Mar 31, 2017 8:17 pm

My guess on this one is that, due to high voltages (up to 1.475V when an 1800X is XFRing!?), AMD really really doesn't want the X parts running hot. Crazy voltages, alright, high temps, alright, but both at the same time on the scales seen here could probably generate a serious number of warranty claims for AMD.

I absolutely agree that this is a dumb way to implement it. Need to keep it under 70C to XFR (just to make up a number)? Change the fan curve, not the sensor data.
 
onlysublime
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Sat Apr 01, 2017 12:59 pm

So here is what CPUID HWMonitor is reporting... So just to be clear, I'm supposed to subtract 20C off the temps... I haven't used this kind of software in awhile so if there's a kind soul out there with an 1800X that can chime in on my numbers and whether they're normal for an 1800X, I would very much appreciate it. Or anyone that can chime in on how to read this data.

To be clear, this was taken after a Handbrake encode (so amazingly fast on the 1800X compared to my previous rig!!!).

Image
 
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Sat Apr 01, 2017 1:51 pm

If software hasn't already added the offset then yes, subtract 20*c.

As much as I don't agree with their way of doing it either I believe their line of thinking was as follows.

XFR needs to start at lower temps, so cool it before XFR might want to kick in and XFR at 100mhz on the X series generates more heat. Benefit those who bought an X by tricking the system into keeping it cooler, sooner to give them more headroom. It's easier to keep a CPU cool than to try and bring it's temp down after it has.... Ryzen. Instead of relying on fan profiles, software or other means, they just baked it into the hardware so that regardless of what software you use, it will be more aggressive with cooling. On top of that, they probably assumed (I'm sure correctly) that most software developer with temp readings can add the Ryzen X SKUs into the software to automatically subtract 20*c. So long as those softwares don't negate AMDs odd method of forcing aggressive fan curves for your XFR's benefit.

I guess it beats the heck out of running a piece of software in Windows (Linux, ect) to try and force a fan profile that would have been provided by AMD themselves. Or like Intel and Optane's reliance on a software.

Really want to find out the benefit of it... Someone needs to find a way for the X chips to report normally and benchmark against it with the factory offset. See what all of the hub bub is about.
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Re: AMD Ryzen 1800X temperature reading - subtract 20C???

Wed Sep 13, 2017 7:59 pm

Mine seems to be staying at the 40-45C range. Currently Streaming chrome/hulu on a 50" 4K and doing a 1T data xfer between drives and highest spike is 52C so far, but quickly jumps back down to the 44 range on the monitor software for this MB I'm doing a manual OC to 4.0, thinking of ditching it and just doing stock and an OC on the 1080 to cool it a bit more.

Cooler is Corsair H110i
Ryzen 1800X
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