Vchipset/DDR + AGP VOLTAGE MOD

Vchipset/DDR + AGP VOLTAGE MOD

Updated 05/11/02 by Tim B @ OCWorkbench.com

Original Thread.
http://forum.ocworkbench.com/ocwbcgi/ultimatebb.cgi?ubb=get_topic&f=27&t=000921

All images courtesy of Miikka Kolo here.
http://www.saunalahti.fi/kolo/hardware/K7S5A
And full size larger images here.
http://www.saunalahti.fi/~kolo/hardware/K7S5A/Non%20edited%20pictures/

Gymyforte's AGP Mod+pic
http://www.ocworkbench.com/ocwbcgi/ultimatebb.cgi?ubb=get_topic&f=37&t=000505
Image1

Note: Increasing the chipset voltage increases the AGP and DDR voltages also.

By Pegelius

Location for Resistors to increase voltage to the Chipset(+vcore).

When chipsetvoltage is @default (1.78V), DDR and AGP voltages are @default also (2.5V and 1.5V).

When chipset gets 1.89V (1 kOhm), DDR voltage is 2.68V and AGP 1.57.

When chipset gets 2.19V (260 ohms), DDR voltage is 3.12V and AGP is 1.82V.

So be carefull when playing with chipsetvoltage when you have DDR and AGP mods installed.

Diagram of solder positions for chipset voltage mod - Courtesy of Miikka Kolo
DDR and AGP Solder Points
Chipset and Vcore Solder Points

See HERE for resistor values

Status of Mod.
-AGP mod works (with trimmer can adjust ~1.2-2V, depends on chipsetvoltage)
-DDR-,Vcore- and chipsetmods have gotten multiturn trimmers, so adjusting can really be finetuning... .
-DDR mod range 2.0-3.5+ V (depends on chipsetvoltage)
-figured out that SDRAM mod maybe identical to DDR mod, because another LM358 (near SDRAM sockets) is connected to fet, which is connected to SDRAM socket. Thanks iggy for the heads up. So, ~3 kOhm trimmer soldered to pin 6 and other end to ground should do the trick.

!Caution!: haven't tested myself, so can't confirm.

-also noticed that chipsetvoltage is connected to LM358 noninverted inputs (A and B) through 3.3kOhm resistor. That is propably the reason why DDR and AGP-voltages rise among chipsetvoltage. Solution: disconnect chipsetvoltage and feed 3.3V through resistor with higher resistance. Will it work? Don't know, propably won't test too soon.

By SJP

The VCore mod uses a 10k 18-turn pre-set plus a 10K safety resistor and adjusts up to 2V core.

The VAGP uses a 680 ohm safety resistor and a 5k preset, giving around 1.8V maximum.

The VDDR uses a 220 Ohm resistor and a 5k preset, giving around 2.75V maximum.

The VChipset uses a 220Ohm resister and a 5k preset, which should give a maximum of around 2.25V.

Of course, combinations of chipset and AGP and DDR will give higher voltages.