hysteresis??? I beg your pardon!

[SiliconJon]

Ok, so I'm troubleshooting my system. It keeps locking up. I had two very similar systems running, and the other just died. It WAS the stable one, but testing suggests both the CPU and the motherboard are toast. So I merged the optical drives, hard drive, RAM, and PSU into this one. This one is STILL flaky, despite those materials being 100% stable in the prior system, and I did remove the old RAM to no avail. This makes me believe that the issue is in the hard drive, a thought I had early in troubleshooting, but wasn't confident as it just seemed odd that all the tests I can get my hands on say my hard drive is 100% yet it is causing hard system halts (Maxtor 40g 7200 2MB).

Soooo, I installed VIA hw monitor as I still feel that perhaps the PSU is the culprit, as both the PSU's used in either system were el'cheapo PSU's included with the ChiefTec cases I purchased from NewEgg. Watching the voltage levels, nothing seems to change very much, even when the systems halts. Though I do not know how quickly this program would react & display a sharp voltage change that could cause such a halt.

Here is my question per my title: What is hysteresis temperature? According to Webster's Dictionary:

Main Entry: hys·ter·e·sis
Pronunciation: "his-t&-'rE-s&s
Function: noun
Inflected Form(s): plural hys·ter·e·ses /-"sEz/
Etymology: New Latin, from Greek hysterEsis shortcoming, from hysterein to be late, fall short, from hysteros later -- more at OUT
Date: 1881
: a retardation of an effect when the forces acting upon a body are changed (as if from viscosity or internal friction); especially : a lagging in the values of resulting magnetization in a magnetic material (as iron) due to a changing magnetizing force
- hys·ter·et·ic /-'re-tik/ adjective

According to VIA's website: "Sorry, but there are no records that match your search criteria" AMD had one hit that was a technical document with no explanation of what it means.

No match found here at TechIMO, jus one post that briefly uses the word. No helpful hits on Google, either. That definition doesn't really help me.

VIA's hardware monitor is giving me this error if I do not change the default settings for hysteresis temp: "CPU Tempture Alarm! CPU Temperture is lower than CPU Hysteresis Temperture" - gotta love their spelling!

Windows XP Pro
XP 1700+ (stock)
K7VZA v3 Mobo (KT133a)
512 Samsung RAM CAS3 (was running 256MB CAS2 Crucial)
Radeon 7500 (also tried a Geforce4 MX440)
Maxtor 40Gig (PM, 10,30gig parts)
WD 120Gig 8mb (PS, 30, 90gig parts)
106S DVD
2410A CDRW
onboard AC97
Macron MPT-400 PSU

[meese]

Here is a good example:

A lag between cause and effect.
Think about the thermostat in your house as an example. Set at 70 degrees, it can't switch on and off at the same time, so it switches on below 70 and off above 70.

VIA is telling you to set the temperature within the hysteresis window. If the upper threshold is 40 and the lower is 35 then set it to 37.

[osprey4]

Probably some foreign national trying to translate a perfectly good Asian word into the English equivalent.

[SiliconJon]

Well, thx meese, but I was wondering about thermal effects on electronics, not HVAC or English. And even still, are you saying is is a synonym for threshold?

I know it wants me to reset it, but I would still like to know what exactly it is referring to and what the setting does. From the webster excert (sp?), it has something to do with the usual effects of the (heat?) being (retarded?) when they reach the given (temperature?) Or something like that perhaps?

And sorry, but the word is latin circa 1881, so amd a for the killer (penguin?) Though I do hate when a good word goes bad in a translation.

Added note: VIA HW only updates up to every two seconds, which is not enough to catch a volitile spike unless I get lucky.

[meese]

Its an upper and lower threshold. The area in between is the hysteresis window. Your CPU temp should not exceed either threshold or it will send out an alarm.

[Peter M]

Hysteresis in electronics ... if you have a regulation circuit that switches the regulatory element on at a certain measurement threshold, you must not choose the same point for turning it back Off. The difference between the On and Off thresholds is the hysteresis.

E.g. when you turn the fan on at 70 degrees C, and turn it back off at 69, you'll end up turning the fan on and off five times a second. Annoying. So you give it a bit of hysteresis, turn on at 70 and off at 65 or so.

[ragtop]

Leaving aside the technical definitions of hysteresis........... As far as the VIA hardware monitor software goes, the "hysteresis temperature" is simply the low temperature limit for the CPU or system temp probes. If the temperature drops below the set values you get an alarm. If you get an alarm on hysteresis temp, either you have the setting too high, or the probe is not sending a signal.

I just set them both for 60 deg F, and forget about them - its high temps you're really worried about, not low temps.

[dunbar]

Hysteresis is difficult to 'splain word wise. Meeses post can be expanded a bit (BTW: good post, meese).
For the hardware monitor which is measuring voltages, here is an attempt:

When deciding to go to a high condition, the trip point is, for example, 12.120 at the input of the measurement device.
Once the high condition is reached, here is the diifficulty.
-Without hysteresis, the condition you need to have at the input to the device in order to go to a low condition, would be anything below 12.120;
-With hysteresis having effect, the condition needs to get below 12.120 by some amount, then the change will occur.

With hysteresis, condition goes high at 12.120, goes low at say, 11.880.
Without hysteresis, condition goes high at 12.120, goes low at 12.120.


Sad to say, most measurement devices cannot indicate the very short voltage transients which can cause illegal states in a CPU or a bridge chip or a disk controller. I consider these hardware monitors as so much wishful thinking, because the measurement bandwidth is frequently very poor (so spikes can be totally ignored), and the response time is milliseconds at best, seconds of response time is not uncommon (watch the BIOS setup screen sometime to see what I mean). But SiliconJon already posted that.

PSUs usually get very noisy, as the aluminum electrolytics get dried out, and also the voltages get noisier if the outputs are slightly to moderately overloaded. The former condition usually gets fixed with a new PSU, the latter can be remedied by removing added components.

SiliconJon: IMO, your problem is likely not a PSU issue if the PSU is only a few months old, and has never been operated in an overload condition for extended duration.

If PSU is a year old and seen normal use, only a maybe for it to be bad, but not totally likely.
If it is a year old and has been running at an overload condition for months and months, most likely is bad.
If it is 3 years old and has been driving just under rated loads (or higher loads), running 24x7 for its' whole life, thank it for its faithful service, give it a burial.

Loads refer to each individual PSU output voltage.
The -12 output might be rated at 3 Amps, it can be overloaded by say 10 watts and its voltage regulation would be very poor, but the whole PSU might be running at a sum total of 1/3rd or less of its rated wattage... overload is on a per output basis!!

So, if the PSU has seen (or is seeing) overload on any output, the voltage may get flaky, both while it is overloaded, and possibly even after load is returned to normal, if the output has been run long enough at the overload condition.

[Linck]

Maybe you could just say it is a range within which a device does not get hysterical. You should know that from women.

(Just a joke )

[SiliconJon]

Well, I'm pretty sure I tried another PSU in it when it first got flaky, and before I merged all the new stuff into it. But it was a similar "cheap" PSU, another one included with the ChiefTec cases at NewEgg. I believe it was only $14 more to get these PSU's with the cases, with this one being "400 Watt" and the other being "450" (quotes added because these specs mean little, and are innacurate at best anyway)..

Someday soon I will pick me up a couple extra PSU's of higher quality and give them a whirl to see if that helps. But if my memory serves correctly, this problem has followed the Maxtor hard drive around...but so many repairs makes for remembering old shootings' a lost cause...