Intel revised its voltage regulator documentation the other day.
It confirms that Prescott will chew up a rather considerable amount of power: 78 amps max (page 13). Let me quote (all emphases in text mine):
“System boards supporting [PIV hyperthreaded CPUs] operating at 3.06GHz or higher and processor code named Prescott must have voltage regulator designs compliant to applicable
FMB electrical and thermal standards. For Intel Pentium 4 processors, this includes full electrical support of 70 A . . . specifications and robust cooling solutions to support 63A thermal design current indefinitely within the envelope of system operating conditions.”
It goes on to say:
“For processor code named Prescott, this includes full electrical support of 78A . . . specifications and robust cooling solutions to support 68A thermal design current . . . indefinitely within the envelope of system operating conditions.”
You can see that the numbers for Prescott are up about 10% over that of the Northwood PIV. This could cause some problems with current PIV mobos.
That’s not the point of the article, though:
Intel also put out an “addendum” to the power requirements for its Extreme Edition processors, and here’s what it says (page 15):
“System boards supporting Pentium 4 processor Extreme Edition . . . should have voltage regulator designs compliant to the FMB parameters defined in Table 1. This includes full electrical support of 91A . . . specifications and robust cooling solutions to support 80A thermal design current indefinitely within the envelope of system operating condition.
You can see that Extreme Edition demands much more from a mobo than Prescott, which makes you wonder what mobos can work with it. If a current 865/875 mobo can’t handle Prescott electrically or thermally, it sure as hell can’t handle an EE.
However, there is a silver lining in this cloud for those of you wondering whether or not Prescott will work with your mobo. If it turns out your mobo company says your mobo can handle an EE, it ought to be able (at least electrically and thermally) to handle a Prescott (though it might not overclock quite as much as it might with a newer board).
Intel Proposes A Voltage Cap
These VRM manuals have something new of interest to overclockers. It’s called “Over-Voltage Protection.” You can find it on page 25 of both manuals previously mentioned:
“An OVP circuit should monitor the output for an over-voltage condition. If the output is more than 200mV about the maximum VID level, the VRD should shut off the Vcc supply to the processor.”
In plain English, turn off the CPU if the voltage is .2V about the maximum voltage level.
What is the maximum VID? For the EE, you can find that on page 9 of the earlier referenced document. It is 1.6V.
For Prescott, to make a long story short, it looks to be 1.3V.
How important is this? Immediately, it probably isn’t very important. This is not a feature Intel requires. Rather, it’s “proposed.” What does “proposed” mean? According to Intel, proposed means:
“Normally met by this type of DC-to-DC converter, and, therefore, included as a design target. May be specified and expanded by system OEMs.”
If a manufacturer promises all kinds of voltages for overclocking, odds are they didn’t implement this circuit. However, if a motherboard has limited voltage options, and you propose to fix that with a voltage mod, you might find get to see this cutoff in action.
Something else to keep in mind.