Prescott effects on motherboard power circuits

Motherboards/Intel S775 by KeithSuppe @ 2004-05-10

The Prescott had finally arrived, and knowing the risks I would be taking even after learning of the chip?s defeatist architecture, I went ahead and purchased the world?s first CPU built upon a 90nm process, and compatible (at least initially) with Socket-478. I?m no martyr, however; I?ve done this for you the reader. Knowing Anandtech had tested Prescott up against Northwood, and Northwood bested the 90nm chip in most benchmarks at default speeds, was ancillary to why. This question had to be answered, and furthermore was Prescott salvageable?

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There seem to be a plethora of circuitous ad hoc thermal safety features inherent to Socket-478 power design, all conspiring to lower temperature through the regulation of voltage. Reading through Intel's White Papers pertaining to Socket-478 90nm features, it's almost redundant, how often thermal/voltage regulation is reiterated. Intel is adamant in communicating to boardmakers/end-users that Thermal Clock Throttling always be enabled;

Madshrimps (c)

As Martin stated in his article pertaining to line-3; "...If it's so well designed then why does it need to do crap like this?" I must confess he does make a good point. Of course no decent Reviewer would be worth his/her weight in Silver Solder if they failed to look at both sides of the argument. While these safety features might seem encumbering to the experienced Enthusiast, whom has gone to great length, and expense to install optimal cooling, what about average desktop users? Water-cooling, phase-change, and high-end after-market HSF combo's are the exception to the rule. Intel must design for worst case scenario, or minimum requirements and they have done their homework. Designing redundant thermal safety features is good engineering sense. In fact Intel knows where to throw its resources, and their commitment to the commercial market is spot-on. Business requires dependable, reliable, self-regulating Server's, and Workstations, not overclocking.

Of course this article was written for the Enthusiast, and where such features are concerned, we must go to great lengths to circumvent their effectiveness. Just about every safety feature designed into a processor, is but an obstacle to the Overclocker. So let the Overclocker be forewarned, raising Vcore on Prescott is not advisable at present, nor is voltage modification. Because of Dynamic VID, any such changes may disable the feature, or even worse see the higher Vcore as the base from which Vcore shall fluctuate. If you own a Prescott you've probably seen the range of fluctuation in its operational Vcore.

This is further complicated due to the anaemic power circuitry on Socket-478 boards claiming to be Prescott ready. I would suggest setting Vcore to Auto, instead of manually choosing the lowest voltage. On my Abit AI7 Vcore with the Prescott in socket reads 1.3875V, yet on the Asus P4C800E-dlx Vcore reads 1.365V. It seems each board's BIOS interprets this value perhaps based on feedback from its own circuitry. If you have optimal cooling, the feature can be disabled. Martin suggests opening Wpcredit, and looking for ACPI P_BLK if it there then it seems were on our way. If you have any suggestions on disabling Dynamic VID via Wpcredit, please contact Martin at You may write me as well, and I'll send it along.

We can never expect Intel or AMD to make life easy for the Overclocker/Enthusiast looking overclock their processors to speeds they haven't even announced yet. Our efforts, however; bode well for them; as such performance exemplifies the processor's performance potential. Albeit just a fraction of total sales, we may be the most loyal; we are also the most fickle. Our demands and our criticisms are quite often unforgiving. Perhaps there will come a time when the growing Enthusiast market segment will warrant chipmaker's to design a processor, specifically for us. Then again where would that end? The whole point of overclocking is to exploit the manufacturing process. What fun would it be a; "...cause without a Rebel?"

// Keith Suppe (Liquid3D)

Questions/Comments: forum thread
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