After my failure on remote sensing (ATX PSUs can't be remote sensed easily), I decided to go another route to control the Vcore fluctuations.
My mobo uses the HIP 6021, but this applies to any programmable Vcore regulator (you need access to the VID pins).
This circuit uses the same PWM regulator than you can find in most ATX PSUs (TL494).
The principle is to add a second stage of regulation (the first stage being the one on the mobo), driven by an ultra accurate voltage reference (I found some 0.1% references), that will switch dynamically one of the VID pins to correct unsufficient Vcore regulation.
The second stage is more accurate than the first stage because it does not handle the high current to the CPU, and because it uses a high precision voltage reference.
Here is the schematic I came up with:
sh.., the link does not work.
here is the URL, copy-paste it in the address bar:
http://www.geocities.com/alochin/temp/Stabilizer.jpg
Or try this:
The Vcore regulator must be switched between two consecutive settings, so that its fault detection will not trigger.
The second stage must switch 1/10 or lower the speed of the first stage.
Datasheet of the TL494:
TL494
I am planning on building and trying this circuit.
What do you think?
[ 12-20-2001: Message edited by: GigaFrog ]