-- Veröffentlicht durch BDKMPSS am 4:32 am 26. Juli 2004
OK, now I now how it works
-- Veröffentlicht durch osl am 21:57 am 25. Juli 2004
I do not fully understand it myself, but it has to do with slightly increasing (or decreasing for overvolting) the current (I) to input Pin 1 and the KA7500C will compensate and ultimately lower (or rise) the output voltage.
Increasing the current (and lowering the output voltage) is achieved by letting a little more current come through resistor connected to plus (+). Decreasing the current (and rising the output voltage) is achieved by bleeding of a little current through a resistor to minus (-).
Overvolting this way has already been proven (Kevin Cribbs ref.), but reversing this and undervolting this way was my own idea.
I have included the internals of the KA7500C (maybe somebody can explain better how this works).
OSL
-- Veröffentlicht durch BDKMPSS am 4:58 am 25. Juli 2004
:noidea: wie hat er das gemacht? (ich meine jetzt nicht wirklich, aber Warum setzt das borard die V-Core runter???)
-- Veröffentlicht durch nubbi am 11:30 am 24. Juli 2004
congratz :)
-- Veröffentlicht durch osl am 0:19 am 24. Juli 2004
-- Veröffentlicht durch osl am 14:39 am 17. Juli 2004
The KA7500C undervolting mod works perfectly. One (5 cents) 270K resistor betwen pin 1 and pin 12 and Vcore is down 0.3 V and temps down 7 degrees (and everything is stable). Tests show that there is a nice linear correspondance between Vcore and the resistor value: Vcore = 1 + (R/1Mohm) V
Underclocking (or undervolting) made easy.
OSL
-- Veröffentlicht durch CMOS am 18:16 am 15. Juli 2004
do the pinmod i showed and cut all L11 bridges on the cpu and it should work!
@dergeert .. er hat nen mobile mit 1.35V default spannung, also sollte es gehen
-- Veröffentlicht durch dergeert am 15:16 am 15. Juli 2004
attention, guys....
there is no pinmod to lower the voltage, and ther never will be....
you always get combinations of the bridge-configuration on the cpu and the pinmod-config. so all you can do without cutting any bridges on the cpu is raisa da vcore ;)
first thing to do is cut all the bridges but one on the cpu to get 1,1v... then you can uncreas voltage by pinmod, not before i'm afraid :(
-- Veröffentlicht durch KakYo am 13:01 am 15. Juli 2004
If this mod really works (i don´t believe it:lol:) you have to use a Monitoring software oder something else...
-- Veröffentlicht durch osl am 12:41 am 15. Juli 2004
Maybe this is a stupid question, but where should I measure the resulting Vcore after the mod ? Does the Bios show the actual Vcore after the mod ?
OSL
-- Veröffentlicht durch osl am 23:13 am 14. Juli 2004
Thanks. Will try it if my current KA7500C mod fails.
OSL
-- Veröffentlicht durch CMOS am 20:36 am 14. Juli 2004
this is viewing the socket from above. do this pinmod for 1.35V
-- Veröffentlicht durch osl am 15:11 am 14. Juli 2004
Could you include a picture of the pin mode required for conly hanging Vcore = 1,35V (all the other parameters and pins confuse me)
OSL
-- Veröffentlicht durch KakYo am 11:54 am 14. Juli 2004
Ah:lol:
Now I understand...
On my nforce2 the XP-M 2400+ 45W is also detected with 1,575V Vcore.
I dont know if it works how you described but I would test if it is possible to use the PinMod (On the left---Workshop---Pinmod) to set a Vcore of 1,35V or 1,325V:noidea:
-- Veröffentlicht durch osl am 11:50 am 14. Juli 2004
I have a XP-M 2400+ Barton 35w and it is running with the MOBO, but it gets pretty hot with the Vcore 1,58V that the bios defaults to.
I was thinking about wiring a large resistor between KA7500C Pin 1 and Pin 12, but I am not sure that it works.
-- Veröffentlicht durch KakYo am 11:30 am 14. Juli 2004
Ähmm yes, it´s possible, but you´ll need a goog CPU, i don´t think that a normal XP2400+ for example an AIUHB will make the 2000MHz@1,35V...
You´ll need a good CPU like a very good JIUHB dlt or better a Mobile CPU like XP-M2600+
Another way could be to lower the Speed of the CPU...f.e. 1,5GHz@1,35V should be possible with an 2400+.
edit: I don´t think that you have to mod your Board, a simple Pinmod should be enough.
edit2: A "reverse-Vcore-Mod" on the board should be hard to realize, because if you use a "Widerstand" (I dont know how to translate) the Board thinks the Vcore is too low and it gives more "Spannung" (Power:)) A higher "Widerstand" brings a higher Vcore but I don´t think that it is possible to mod the board that way, that it brings a lower Vcore
Oh my god, Two years out of school and such a bad english:lol:
(Geändert von KakYo um 11:41 am Juli 14, 2004)
-- Veröffentlicht durch CMOS am 11:18 am 14. Juli 2004
first off .. what cpu do you have ?
and yes there is a simple mod, called pinmod ... you´ll find it here
just put some wire in the socketholes needed!
-- Veröffentlicht durch osl am 21:54 am 13. Juli 2004
Underclocking: Is it possible to lower default Vcore 1,58V to 1,35V (true XP-M 2400+ 35W Vcore) using some simple mod (for the KA7500C SMPS controller) for KM400 motherboards, like PCCHIPS M851LU, Matsonic MS8188E, Shuttle MK40VN ?
Reason ? I think the picture explains it all !
Regards,
Ole Steen Larsen
Denmark
