hysteresis...?? and other via hardware monitor questions 1

[compnut24]

what is:
CPU hysteresis?
System hysteresis?

And what do all of those other features on my hardware monitor mean?

Also, what is the normal operating temp for a 1ghz amd? At what temerature do things begin to...freeze/die, or melt?

-Thanks

 

[Eguy]

Hi;

This is what I found.

Normally, you run your CPU at full speed. Which generates a lot of heat. If your system cooling is inadequate then the CPU temperature will reach the alarm temperature at some point.

What happens then is (though I'm not sure if it's currently implemented or not) the system automatically lowers performance in order to cool off.

But if the system was set up to switch back to full speed immediately after the temperature dropped below the alarm temperature you would get a lot of high-frequency switching.

Basically - the full-speed mode very quickly makes the CPU exceed the alarm temp, then it slows down and quickly drops below, then it speeds up and quickly exceeds again. This isn't good for the CPU at all.

Enter the hysteresis temperature. Once the CPU slows itself down, it won't go back to full speed mode until it reaches the hysteresis temperature. It's effectively an artificial delay in the switching cycle. You see the same thing in thermostats and other simple feedback systems.

Same deal for the system alarm and system hysteresis temperatures.

As far as "normal" temperatures go the CPU will get cranky around 60C (140F). I'm using an AMD Athlon 1.2G and it usually is around 121F - 135F. As I write this it is at 131F.

Hope this helps.

Ed

 

[hotfusion]

That's right, hysteresis is really a 'no-man's-land' area within a system's response, either introduced artificially to reduce hunting between levels, as in the above case or existing naturally as in when, for example, something magnetic is exposed to a magnetic field. My suggestions are what I would try myself. If incorrect, I welcome corrections to my knowledge. Andy.

 

[compnut24]

thanks for your response guys. My question now is: What temps. should i set my different hardware monitor fields to?

-Skyler

 

[Eguy]

Hi Skyler;

I'm using the default values myself and that seems to be OK

CPU overheat temp 140 F
CPU hysteresis temp 104 F
System overheat 122 F
System hysteresis 104 F

For the fan speeds I use 50% of its normal speed

Voltages 110% & 90%

Another safety check you might want to consider.
See if your BIOS has an option to prevent power-on if the CPU fan is not connected/running.
That little feature save me once.
I was adding memory and had unplugged the fan. Well of course I never plugged it back in. System wont start. Im mad. Finally saw it. It saved me.

Funny, but I didn't feel stupid.

Hope this helps

Ed

 

[paparazi]

Defaults are fine!! 50 degrees C CPU alarm sounds low! especially when you first put your system together and get max's of 65 plus!!!! like I did!! I was asking the same questions and thankfully with the addition of 3 standard 80mm case fans my max CPU temp has come down to 43C (yes! it is possible)
AMD official info says a 1 gig absolute max is 90C
But with a calculation they supply (see

http://www.overclockers.com/tips400/)the

constant max they sugest is around 71C.AMD obviously set this very high figure as the max the CPU should be run at constantly but a much lower temperature is prefered and can easily be obtained.
Having said all of this with ambient air temps of between
20-30 degrees C it is easily possible to get your CPU max down in the mid 40's, If you require futher details Email me on martin_@ntlworld.com Martin.
(after hard 3D gaming) down in the mid 40's C.

 

[compnut24]

thanks! Yeah, i added 3 case fans, mine usually runs at 41c now, which sounds pretty good to me...

 

[Guest_imported]

I just build a new Atlon XP 1700+ and my CPU temp stays around 39C or 102F. I hope this is good. I have my setting cranked thanks to my Crucial DDR ECC Registered mem. I need to ad some internal case fans to improve flow.

 

[Guest_imported]

I have Via Hardware Monitor running and an alarm keeps appearing "CPU temp is lower than CPU hysteresis temp. WHat does this mean. I have an AMD 950 overclocked to 1050mhz

 

[Eguy]

Steve293;

What are your settings? Hysteresis temp is a user setting telling the CPU that it has cooled down enough to resume full speed. Your normal(?) temperature is outside of this range.

Ed Please let me know if the sugestion(s) I provide are helpful to you.
Sometimes your the windshield... Sometimes your the bug.

 

[Guest_imported]

The CPU hysteresis temp is set at 104F the overheat temp is set at 122F. Although is actually runs at 87F. As for the System hysteresis it is set at 104F also and the overheat is set for 122F. But the usual system temp stays around 64F The settings ont the Via HM are the default settings, do I need to change them?

 

[CyberVenom]

I would say, set your hysteresis temp to a little below your normal operating temperature, and it should fix your alarm. 39C is quite good for an AMD XP 1700+. Mine with a copper fan-fin heatsink, 3 case fans, power supply fan, system fan, and GPU fan runs at 43C. (I just burned out my 1400 by running without a heatsink while defeating the CPU-Fan safety check... stupid me - I wouldn't let the BIOS save me. It was pretty spectacular though: The seal on the CPU blew, molten sealent spewed out the side and it started smoking, all within 10 seconds of powering up!)

 

[Guest_imported]

Hi ppl I have a xp1800+ runs at 55c (129F),its wicked stable i got a cpu-fan, PS-fan and gpu-fan. I run it at a MSI K7T266-R i use PC alert III to monitor stuff. I'd say dont worry if your system is stable PC alert III default CPU max 75c (alarm).BUT....theres several ways of measuring.

1 airflow
2 UV

i dont know which of the above is closer to the actual value but i know they differ (i read an article about a MB that pointed out this subject).

So....50c on one MB can be 53c on another.

dont panic if your cpu is running below 75c and stable go play games instead of worry about temps

 

[Guest_imported]

I just read an article where they had a thermocouple as measuringinstrument.

learning.....

thermocouple is either 2 pieces of metal causing current due to temp. or temp conductivity.

mike

 

[CyberVenom]

A thermocouple can also be used in the opposite manner:
A current thru the device induces a flow of heat energy from one side to the other. This device is known as a Peltier Heat Junction. Some (crazy) people use these devices to cool their CPUs, forcing the heat to flow from the CPU into the heatsink faster than conduction would normally cause it to move. Unfortunately, when a Peltier heat junction burns out, it will end up operating as an insulator, prohibiting the flow of energy it once aided. When that happens, your CPU doesn't stand much of a chance - especially AMD CPUs that rely heavily on the heat sink to prevent overheating.