Internal Thermal Diode of new Palomino cores...

[Insane3D]

I have a few questions regarding the Thermal Diode included in the new Palomino cores from AMD.

1. I am aware these give an accurate temperature of the core, but do they also shut the CPU down before it burns itself up, like the Thunderbird cores would do?

2. If the answer to #1 is yes, how does it accomplish the shutdown..via a Halt command?

3. Can a current Socket A motherboard have support for reading the CPU temp added in a simple BIOS update, or is it more involved, requiring physical modifications to the board?

4. If physical modifications are needed, what would those be?


Thanks in advance..

 

[jamison]

I think I read that yes, the CPU does shut down before "melt down".

Also I think I might have read that a current Socket A motherboard will be fully compatable with the Palomino's with a BIOS update.

Not 100% sure but I am sure someone more knowledgable will confirm or throw out my answers.

 

[Wingznut]

I could never do the explanation justice, as I really don't understand it, so I won't bother to try to explain. Other than to say that I'm almost positive that a BIOS flash cannot make use of the thermal diode. I imagine it would require different circuitry, including a logic device, on the motherboard to read the new diode.

 

[bevo]

Insane3D...I don't believe any of the present MBs can use this feature...

 

[Insane3D]

"Insane3D...I don't believe any of the present MBs can use this feature..."

One can..the Tyan duallie board..that's it at the moment.

 

[MCS]

If you know for a fact that the Tyan board supports it then it's pretty fair to say that it has to be supported in hardware. I believe the diode is read via a specific pin on the CPU therefore this has to be connected to something which knows how to read it.

 

[Killbat]

"I believe the diode is read via a specific pin on the CPU therefore this has to be connected to something which knows how to read it."

If this is so, and if the gods are kind enough to have made the diodes compatible, a simple jumper wire from that pin to the extra temp probe input on some motherboards would do the trick.

*goes off to find Palomino pinouts*


[edit]
OK, for all those interested, the Athlon MP datasheet is available here.
There are pins on the chip that correspond to the thermal diode's anode and cathode. The diode specifics are in section 7.13
I haven't found mention of an automatic shutdown yet...

[edit]
I whipped up a simple pin diagram. Take a look at it here, share with your friends.
So what you'd want to do, assuming the diode has the correct characteristics and your motherboard supports an extra probe, is run two wires from those pins on the socket to the appropriate two header pins on the motherboard. Bonus.

 

[Adul]

Nice find killbat, now to see if that works.

 

[pm]

Maybe I'm off base here, but I thought the motherboards' probes are thermistors (resistors that are strongly sensitive to thermal changes) while the on-CPU devices are diodes (pn junctions). I can't imagine that hooking up the CPU diode to the chipset as if they were thermistors is going to work correctly.

 

[CTho9305]

one issue - getting the wires out once the cpu is in the socket. is there space? if not, do those pins to through the back of the board? then it would be easy to solder the wires on the underside

edit: pm types faster thats a good point. but I assume that it either always conducts or always blocks - you could theoretically get a high-power transistor and use the diode on the control... put it on the AC line into the power supply and you have instant protection. except you get no warning

 

[kormaster]

dang!! i want one!!

 

[pm]

You could wire it to the pins by doing a very shallow wire-wrap. This isn't the problem IMHO. The problem will be getting the diode to act like a thermally sensitive resistor that has the same properties as a 10k thermistor.

Personally, I would think it would be easier to breadboard up a diode voltage-bias circuit, send the output that to a a->d converter, send that to the serial port, and read the values off of the serial port with a short Visual Basic program. But all this will be more expensive and time-consuming than simply buying a new motherboard.

 

[CTho9305]

but MUCH more interesting than buying a new motherboard

 

[Killbat]

I had another thought. Do motherboards typically use thermistors or diodes for the temp sensor under the CPU socket? If they use diodes there, you could just yank the external sensor out and wire the pins right there.

 

[DDad]

Off Topic- Hey- Great to see you PM!

 

[Adul]

they use thermisters Killbat.

 

[CTho9305]

would a diode have any in-between stages, or just on/off (well, conducter / high resistance)? even so... you could probably add whatever resistance is necessary so in the normal state the mobo would read like 30C, and in the "bad" state, the mobo would read 100C or something like that.

 

[Insane3D]

Great info you guys..thanks! Keep it coming...

 

[MrThompson]

An industry insider told me that some of the high end new boards will not feature a socket thermistor and have a hole in the motherboard at the center of the Zif socket to facilitate secondary heatpath cooling. Expect to see cooling fans on the back side of the Zif socket. Abit, Asus and Soyo tradationally offer on die thermistor reading for Intel CPUs so I would think they will be the first companies offering this feature.