What's the *real* speed?

[EndUser]

Pentium 4 1.5Ghz reads 100Mhz x 15? Wouldn't you get better results with a 133Mhz x 11 = 1.463 Ghz? And, while I understand why Pentiums might be locked to keep from being overclocked, why can't the be underclocked? And what is the difference between the 423 pin chip and the 478 pin (besides the count)?

 

[AdamK47]

Enduser, the name fits you well. As obvious as it seems, it would be better to run at 133 x 11. The problem with that is the original i850 is designed to run the CPU at 100MHz on a QDR bus (400 QDR) with the RDRAM at a 400MHz DDR speed (PC800). There may be plans in the future to expand upon the i850 and support higher bus speeds and increased memory speeds with the Northwood.

Just like any CPU, the P4 can be underclocked as long as either the multiplier or bus speed can be set lower. In the case of the multiplier locked P4, the later is the option just as long as the motherboard supports it.

The difference between the 423 pin and 478 pin P4 besides the pin count is the packaging. The 478 pin CPU is much much smaller and requires less manufacturing costs.

 

[Bobek]

Yes, that´s right. No possibility to change multiplier of P4 (unlike the Athlons), so running it "~on specified frequency" with 133MHz FSB is not possible (but hey, it´s possible to overclock it ). The P4s will migrate to 533MHz bus (133MHz QDR) in Q1 or Q2 next year with the release of the Northwood core. First chipset supporting 533MHz FSB will be Intel 845E/G (with DDR memory support) and a version of Intel 850 with support of PC1066 RDRAM.

- edit -
Sorry, there should be modified versions of SiS 645/650 and maybe VIA P4X266A/333 chipsets available for 533MHz FSB P4s at the same time as Intel 8whatever. But I still think it will be first (probably for few hours )

 

[Jerboy]

<< Yes, that´s right. No possibility to change multiplier of P4 (unlike the Athlons), so running it "~on specified frequency" with 133MHz FSB is not possible (but hey, it´s possible to overclock it ). The P4s will migrate to 533MHz bus (133MHz QDR) in Q1 or Q2 next year with the release of the Northwood core. First chipset supporting 533MHz FSB will be Intel 845E/G (with DDR memory support) and a version of Intel 850 with support of PC1066 RDRAM.

- edit -
Sorry, there should be modified versions of SiS 645/650 and maybe VIA P4X266A/333 chipsets available for 533MHz FSB P4s at the same time as Intel 8whatever. But I still think it will be first (probably for few hours ) >>




whaaaaaaaaaaat? Pentium 4 has 100MHz FSB??

 

[Spikesoldier]

<< whaaaaaaaaaaat? Pentium 4 has 100MHz FSB?? >>



No, a Quad-Pumped 100MHz FSB. 100MHz*4=400MHz