Questions on a +3.3V PSU Mod have come up several times, so I prepared following mod description. The idea is to raise the +3.3V bus for the purpose of delivering a higher Vdimm to BH-5 or UTT memory modules. This of course, only works if the +3.3V bus has been previously connected to the Vdimm line on the Motherboard. The 3.3Vdimm mod will be outlined in sector for your Motherboard, if the board is capable of being modified. Not all can be modified.
The top sketch shows a typical PSU connected to a motherboard. The mod requires you to find the "Grey" "Remote Sense" lead for the +3.3V bus and install a series 100 Ohm resistor as shown in the lower sketch. The "Grey" "Remote Sense" lead is inserted in one of the "corner" pins on the PSU's ATX connector, along with a Orange +3.3V lead. It is usually Pin #tbd...
The Mod is to first cut the Gray sense wire, then connect a 100 Ohm resistor in series with that wire by connecting one end of the resistor to one of the Grey wires ends, and then connecting the other grey wire to the other resistor end. Do not remove the Orange & Grey wire from the ATX socket. After the 100 Ohm resistor is connected as shown, an adjustable 10K resistor and a series 1K resistor need to be connected across the "Remote Sense" lead and any one of the "Black" ground leads... The 1K resistor is to keep the adjustable resistor from causing a overvoltage shutdown, when it goes to 0 Ohms. The spec on the 3.3V is 5%, so adjusting the +3.3V to +3.465V will mean the 3.3V rail is still in spec. Any voltage higher then +3.465V, is a risk you must be prepared to take. The mod shown below, will be capable of approximatly a 10% increase of Vdimm, or 3.63V.
If you do this mod, your doing it at your own risk. The Rebels Haven Computer Forum will not be responsible for damaged systems or components... If your unsure about the mod, I strongly suggest you do not implement it...
Damn Phenoms!
