Credit goes to The Stilt for the volt and cap mods...I am just posting them here since I just completed them on my P5WD2, so I will add some of my own notes. Standard disclaimer: do these mods at your own risk! If your mobo blows up, it's YOUR fault and you've voided your warranty in the process.
This is to show where the mods go and where the measuring points are. "Vddr mod" allows control of the memory voltage. "MCH volt mod" allows control of the Northbridge voltage. Adding the capacitor should stabilize the MCH voltage and eliminate the reboot problem. Also note there are two empty (but powered) locations that fan headers can be installed: one for the Northbridge and one for the Southbridge. If you need some extra outputs for fans or plan to actively cool either of those sinks, you might be interested.
Prior to doing any of these mods, I measured actual voltages on the board compared to what was set in BIOS (rev. 0304).
Vddr (BIOS setting = Measured):
AUTO = 1.757V
1.80V = 1.758V
1.90V = 1.819V
2.00V = 1.952V
2.10V = 2.030V
2.20V = 2.163V
2.30V = 2.223V
MCH (Northbridge) Voltage (BIOS setting = Measured):
AUTO = 1.447V
1.50V = 1.534V
1.55V = 1.577V
1.60V = 1.534V
1.65V = 1.577V
Anyone else find it a little odd that the "even" settings (1.50V and 1.60V) yielded the same measurements while both the "odd" settings (1.55V and 1.65V) also yielded the same measurements?
To perform both the MCH voltage (Northbridge) and Vddr (memory voltage) mods, you will need 2 variable resistors. I am using two 10K Ohm cermets. I am also using a 470mF 16V high-temp capacitor for the cap mod, which should be available just about anywhere. FYI, The Stilt used a 6.3V cap of the same capacitance.
Before tearing the system apart to do the mods, make sure to set your DDR Voltage and MCH Voltage to AUTO in BIOS!
If you need some possibly better pics, see The Stilt's write-up.
Let's start with the MCH voltage mod. First, locate the correct chip as shown in the top photo (RT9214). Measuring resistance between pin #6 (voltage feedback) and Ground (or pin #3), it should be around 460 ohms (mine was 458). All that needs to be done is to connect one side of the VR to the #6 pin and the other side of the VR to Ground. The #3 pin on the RT9214 is Ground, so I simply connected the VR in between pins #3 and #6. Here's the spec sheet/schematic on the RT9214 in case you are interested.
An RT9214 chip is also used for the Vddr voltage, so the same pin(s) apply. One side of the VR to pin #6 and the other side of the VR to Ground or pin #3. Just make sure to note that the Vddr RT9214 chip is oriented 180° opposite from the MCH RT9214, so double check that you are on the correct pin(s) before soldering! FYI, on the Vddr RT9214 chip, resistance between #6 and Ground (or pin #3) should be around 580 Ohms (mine was 582).
Unlike the MCH VR where there was no empty space close to the chip to mount it, I was able to mount the VR for the Vddr mod right next to the chip and the legs of the VR were long enough to reach the pins directly.
VERY IMPORTANT: Set the resistance of the VRs BEFORE turning the PC on for the first time! I set mine (and labeled them) before I even plugged in the soldering iron. I preset the MCH VR to 7K Ohms and the Vddr VR to 5K Ohms (6K preset would be closer to default voltage).
Last, but not least, add the capacitor to the blank shown. Make sure to note that the white shaded side of the circle on the mobo denotes the POSITIVE side. Polarized caps have to go in the RIGHT way or they will burn up when power is applied. It took several attemps to get the filler solder out of the mobo with a crappy 30W iron and a manual solder sucker....I guess that StackCool2 on the back works!
The results:
With the MCH VR preset to 7K Ohms, measurement with the MCH Voltage on AUTO was now a beefy 1.67V (compared to 1.45V stock). The stock NB sink isn't burning hot with a currently caseless mobo and HSF, but in a case and/or no HSF (WC), the NB sink should probably have a fan, especially for higher voltage. With the Vddr VR preset to 5K Ohms and AUTO setting in the BIOS, measurement for it was now a nice even 2.00V (compared to 1.76V stock). Higher initial resistances on both VRs will reduce the new voltages and make the first post-mod start-up a little less "dangerous".
Remember that with AUTO set for the voltages in BIOS, whatever you set the measured voltage to with the VR is the lowest it will ever be and they will be raised a corresponding amount when upping voltage in BIOS. So, rather than set them based on the AUTO BIOS setting (lowest), I maxed out each BIOS setting and set the VRs to give the highest possible voltages I'd want to run for now. Any lower setting in BIOS will now yield lower and safer (but higher than stock) voltages.
Enjoy!
This is to show where the mods go and where the measuring points are. "Vddr mod" allows control of the memory voltage. "MCH volt mod" allows control of the Northbridge voltage. Adding the capacitor should stabilize the MCH voltage and eliminate the reboot problem. Also note there are two empty (but powered) locations that fan headers can be installed: one for the Northbridge and one for the Southbridge. If you need some extra outputs for fans or plan to actively cool either of those sinks, you might be interested.
Prior to doing any of these mods, I measured actual voltages on the board compared to what was set in BIOS (rev. 0304).
Vddr (BIOS setting = Measured):
AUTO = 1.757V
1.80V = 1.758V
1.90V = 1.819V
2.00V = 1.952V
2.10V = 2.030V
2.20V = 2.163V
2.30V = 2.223V
MCH (Northbridge) Voltage (BIOS setting = Measured):
AUTO = 1.447V
1.50V = 1.534V
1.55V = 1.577V
1.60V = 1.534V
1.65V = 1.577V
Anyone else find it a little odd that the "even" settings (1.50V and 1.60V) yielded the same measurements while both the "odd" settings (1.55V and 1.65V) also yielded the same measurements?
To perform both the MCH voltage (Northbridge) and Vddr (memory voltage) mods, you will need 2 variable resistors. I am using two 10K Ohm cermets. I am also using a 470mF 16V high-temp capacitor for the cap mod, which should be available just about anywhere. FYI, The Stilt used a 6.3V cap of the same capacitance.
Before tearing the system apart to do the mods, make sure to set your DDR Voltage and MCH Voltage to AUTO in BIOS!
If you need some possibly better pics, see The Stilt's write-up.
Let's start with the MCH voltage mod. First, locate the correct chip as shown in the top photo (RT9214). Measuring resistance between pin #6 (voltage feedback) and Ground (or pin #3), it should be around 460 ohms (mine was 458). All that needs to be done is to connect one side of the VR to the #6 pin and the other side of the VR to Ground. The #3 pin on the RT9214 is Ground, so I simply connected the VR in between pins #3 and #6. Here's the spec sheet/schematic on the RT9214 in case you are interested.
An RT9214 chip is also used for the Vddr voltage, so the same pin(s) apply. One side of the VR to pin #6 and the other side of the VR to Ground or pin #3. Just make sure to note that the Vddr RT9214 chip is oriented 180° opposite from the MCH RT9214, so double check that you are on the correct pin(s) before soldering! FYI, on the Vddr RT9214 chip, resistance between #6 and Ground (or pin #3) should be around 580 Ohms (mine was 582).
Unlike the MCH VR where there was no empty space close to the chip to mount it, I was able to mount the VR for the Vddr mod right next to the chip and the legs of the VR were long enough to reach the pins directly.
VERY IMPORTANT: Set the resistance of the VRs BEFORE turning the PC on for the first time! I set mine (and labeled them) before I even plugged in the soldering iron. I preset the MCH VR to 7K Ohms and the Vddr VR to 5K Ohms (6K preset would be closer to default voltage).
Last, but not least, add the capacitor to the blank shown. Make sure to note that the white shaded side of the circle on the mobo denotes the POSITIVE side. Polarized caps have to go in the RIGHT way or they will burn up when power is applied. It took several attemps to get the filler solder out of the mobo with a crappy 30W iron and a manual solder sucker....I guess that StackCool2 on the back works!
The results:
With the MCH VR preset to 7K Ohms, measurement with the MCH Voltage on AUTO was now a beefy 1.67V (compared to 1.45V stock). The stock NB sink isn't burning hot with a currently caseless mobo and HSF, but in a case and/or no HSF (WC), the NB sink should probably have a fan, especially for higher voltage. With the Vddr VR preset to 5K Ohms and AUTO setting in the BIOS, measurement for it was now a nice even 2.00V (compared to 1.76V stock). Higher initial resistances on both VRs will reduce the new voltages and make the first post-mod start-up a little less "dangerous".
Remember that with AUTO set for the voltages in BIOS, whatever you set the measured voltage to with the VR is the lowest it will ever be and they will be raised a corresponding amount when upping voltage in BIOS. So, rather than set them based on the AUTO BIOS setting (lowest), I maxed out each BIOS setting and set the VRs to give the highest possible voltages I'd want to run for now. Any lower setting in BIOS will now yield lower and safer (but higher than stock) voltages.
Enjoy!