PSU Voltages

[Snakeyeskm]

By changing the PSU voltages 12v,5v,3.3v would the mother board voltages change to PCI,AGP Memory etc ?
Would the changes be consistent across the three voltage settings, or would the mobo adjust them differently ?
I am getting conflicting opinions on this issue and would appreciate any clarification

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[G0AOZ]

Exactly how are you proposing to change the PSU voltages? And why would you want to do this unless you have a desire to kill the motherboard and all other components! As far as I'm aware, each low voltage dc output is independently stabilised. So if you made minor adjustments to the 5v stabilisation circuit, it probably wouldn't affect the 12v or 3.3v outputs. However, bear in mind that dramatic alterations could affect the other circuits as they all come from the same source.

This very definitely needs a "skull & crossbones" label on it, particularly if you're intending to delve about inside the PSU amongst the lethal voltages lurking within.


ROGER - G0AOZ.

 

[mainegeek]

Basically, the PS converts AC to DC at a steady supply to
+3.3v +5v +12v -5v and -12v and if all is well, sends a Power Good signal to the mobo.

Before the +3.3v was available, the +5v was used and converted to +3.3v through voltage regulators on the mobo.
This also generated additional heat.

The +5v is used by the mobo and if I recall the -5v was used by older floppy controllers and the -12v is/was used by the ISA Bus for backward compatability and a small amount for serial.

The +12v is used to run drive motors.

There usually is a fluxuation +/- but I don't know off the top of my head what is acceptable.

Don't know if any of this has helped you.

 

[Snakeyeskm]

Mainegeek, Thanks for the feedback, it was helpful.

G0AOZ Occers have been modifing mobo voltages for ages. Many Bios allow voltage changes. I am trying to get a better understanding of the process. I really don't need nor did I ask for any "label" . I have played with PSU's and Have built several Computers from scratch. One of my present PSUs is a 'PC Cooling" PSU that is a top end PSU and has adjustable voltage Pots built-in into the PSU.

Zero Mistakes = Zero Experience
And Boy do I have experience !

 

[Tarwn]

As far as increasin gthe coltage for overclocking, you generally only want to change the VCore (+1.5). The best way to do this is in very very small increments until it fails to load into windows/shows blue screens/crashes/etc, then back it off a couple of settings to a more stable configuration.

For example, I have an ASUS P4P800 with an older P41.6A on it. I couldn't push the processor further than about 1.9Ghz without getting crashes. I increased the VCore from 1.5 to about 1.525 and now I am stable at 2.16Ghz (30% overclock).

Generally I have found that softqware OverVolts (via BIOS) are a little easier than hardware (via toggles on the motherboard, etc). The reason for this is most newer motherboards have failsafe settings so that if you did accidentally bump your vcore to far without noticing, some will actually detect the overvoltage and drop top failsafe settings.

You should also look into what the nominal voltage is for the CPU your using. This is slightly differant for differant CPU manufacturers. Also realize that over-volting definately shortens the life of a processor as a tradeoff for making it work harder, ie work harder for a shorter period or work normal fo a longer period. Time vs power.

Hope this helps,
-Tarwn

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[Snakeyeskm]

Thanks for the feedback Tarwn
I built my PC with a ASUS p4T533-c ths bios of which allows me to change the CPU VCore volts. Its interesting that ASUS builds in a VCore overvolt in its default.
I am presently running my P4 3.06 at 3.33 with stock VCore and stable thru memtest as well as 24 hours of Prime.
I agree excess VCore will overheat the CPU and thus shorten its life. I am using a Zalman7000Cu CPU cooler which even at overclock keeps temps at 29c idle and 42/45 full load.
I was interested in the possibility of slightly increasing my 3.3v rail so as to indirectly increase my Vrimm volt to the RDRam for further stability.

Zero Mistakes = Zero Experience
And Boy do I have experience !