Erratic readings and brief way over TJMAX. Normal?

A place to discuss topics related to Core Temp
Post Reply
DrHow
Registered User
Registered User
Posts: 3
Joined: Wed Apr 02, 2014 11:51 pm

Erratic readings and brief way over TJMAX. Normal?

Post by DrHow »

I am using Core Temp 1.0 RC7 on an AMD A10-5700 running Windows 8.1. Compared to my Core Temp experience with Windows 7 on an AMD Phenom and XP on an AMD Athlon, I am seeing some things that surprise me.

The temperature reading is very erratic. It can jump up more than 10degC in a single 1-second sample. Then it typically lowers itself over the next several seconds back down to hovering around 50. (This is when nothing big is going on.) TJMAX is listed at 70; but some of the jumps are well over that. Indeed, after Core Temp has been running for a few hours, I will generally see a reported max as high as 84. With TJMAX at 70; that tends to worry me. Should it?

It never behaved this way with the other systems. With them, temperature changes were always gradual. I am using a beta version because the release version did not work at all. Could this erratic behavior be misbehavior? Or could it be that there is a lot less thermal lag between the sensor and the source of the heat with these new APUs? Could it be that the power regulation is agile enough that the brief high temperatures can be ignored? Would it make sense to introduce some low pass filtering on the reported temperature to avoid anxiety? E.g., a configurable "average temperature over [parameter] seconds".

User avatar
The Coolest
Site Admin
Site Admin
Posts: 3379
Joined: Tue Feb 18, 2003 7:48 pm
Location: Tel Aviv, Israel
Contact:

Re: Erratic readings and brief way over TJMAX. Normal?

Post by The Coolest »

Sadly the thermal sensors on AMD processors are not very reliable as it seems. Especially on the new APUs.
There is not much I can do from my side since Core Temp can only display the value it reads from the processor.
Main rig:
AMD Ryzen 9 5950X (True Spirit 140 Direct) / Mobo: Asrock Fatal1ty X470 / EVO 970 500GB + WD Blue 250GB + HDD / GPU: Dell RX 570 4GB / Mem: 2x16GB DDR4-3200 G.Skill 32GTZKW TridentZ - 32GB total / PSU: Seasonic Prime Ultra Gold 650W
NAS:
Core i7 2600K 3.4GHz @ 4.3GHz (Scythe Mugen2) / Mobo: Biostar TP67XE / 2x Inland Pro 120GB + HDDs / GPU: ATi Mach64 VT2 / Mem: 4x4GB DDR3-1600 G.Skill 8GBXL RipJawsX - 16GB total / PSU: Seasonic S12II 620W.
Secondary rigs:
Core i3 7130U / MiniPC / SanDisk SDSSDP-128G / GPU: Intel HD 620 / Mem: 1x8GB DDR3L-1600
Xeon X3430 2.40GHz @ 3.06GHz or Core i3 540 3.06GHz @ 4.0GHz (Freezer 7 Pro) / Mobo: MSI H55M-ED55 / PNY CS1111 240GB / GPU: ATI FirePro V3800 / Mem: 4x2GB DDR3-1600 G.Skill 4GBRL RipJaws - 8GB total / PSU: Seasonic S12II 620W
AMD Phenom II X4 B93 / Mobo: ASUS M2A-VM / GPU: ATI Radeon Xpress X1250 / Crucial M4 120GB / Mem: 2x2GB DDR2-800 - 4GB total / PSU: Antec 380W.

Core Temp - Accurate temperature monitor for Intel's Core/Core 2 and AMD64 processors

Jorge
Registered User
Registered User
Posts: 42
Joined: Sun Jan 06, 2013 11:40 pm

Re: Erratic readings and brief way over TJMAX. Normal?

Post by Jorge »

FWIW the newer FX processors also jump around in temp a lot per-second because of AMD's more sophisticated power states used in these processors and the sampling rate.

I don't believe 70C is the correct TjMax for the APUs as the graphic section can drive the processor temp higher than a normal discrete CPU. The APUs are closer to a notebook type of processor which is designed to run at higher temps because they have limited cooling. Unfortunately AMD sucks at providing technical information on their products and temps are some thing of a national security secret - to AMD. Their advanced power states on the latest Beema/Mullins is also different so expect lots of changes going forward.

You can indirectly find the TjMax if your temp gets too high as the APU will start to throttle the CPU frequency to lower the temp. Under sustained max load the frequency will oscillate back and forth at whatever the true TjMax temp is to prevent the APU from reaching the safety shut down temp. There is no need to worry about it burning up because it will shut-off before that can happen.

Post Reply

Return to “Discussion”