CPU / CORE / FREQUENCY

[Hobit]

Forum Members,

The P4 with a .13 micron Northwood core is capable of stable operation at frequencies of at least 3 GHz. What then are the technical differences between a Northwood core P4 processor sold as a 2.2 GHz processor and one sold as a 2.8 GHz processor?

hobit

[iisbob]

probably it's underclocked by intel, this has been a common practice for years-it's kind of a " Manufacturer " security blanket, they tell you it's rated at 2 GHZ, so that if you OC it, and it runs-great, however if you OC it and it crashes-tough, they didnn't retail it at that speed.

A lot of PI,II's,and II's were sold ( and still are ) as slower than what they can clock at, this is just a standard business practice.



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iisbob

CPU= 5mhz
Memory= 16 K
Storage=10.2MB's
Video=Onboard S3 4K
Modem=14.4 baud
Sound=ISA Yamaha 8bit
Mouse=2 button MS
Monitor=ACER 12.5"
OS= WIN 3.1

My ultimate gaming system :)

[Hobit]

iisbob

Thanks for your response.

In addition to CPUs being "probably ... underclocked by intel ... (as) just a standard business practice," wouldn't they also have to have some means of setting the relationship between CPU operation frequencies and FSB.

Are you aware of what these means might be.

hobit

[iisbob]

Not quite clear what you're asking. But...


Do they { INTEL } set the FSB low? No, this is done by the motherboard vendor, for example; if you get a new motherboard-it may be 133 rated, but odd's are they're running it out of the box at 100. So the P4 you get, while rated from Intel at 2 GHZ, is probably a true 2.4 or higher, so the motherboard manufacturer places this " 2 GHZ rated " CPU on it's board and gives you the BIOS options to run it at a higher clock speed.

Make sense?

Intel ( and Athlon too i'm sure ) actually sell their chips at a tested stable speed; which just means that the particular CPU you purchased is labeld at 2 GHZ because the batch of dies it came from the test chips all crashed at a higher speed, if they stay stable at 2.8 then they are marketed at that speed.

Clearer? http://www.PCGuide.com/ubb/smile.gif




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iisbob

CPU= 5mhz
Memory= 16 K
Storage=10.2MB's
Video=Onboard S3 4K
Modem=14.4 baud
Sound=ISA Yamaha 8bit
Mouse=2 button MS
Monitor=ACER 12.5"
OS= WIN 3.1

My ultimate gaming system :)

[hiredgoonz]

Also, as the manufacturing process for the dies develops, they tend to get better yields. All the chips out of a fab may run at 2.8Ghz stably, but Intel still needs to sell slower chips to provide a price point for all segments of the market...

There will always be a price premium for buying the fastest chip. Intel knows that not everyone wants to pay it, so they mark the chips as much by demand as by the chips' ability to run at a certain speed...

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When all else fails, read the instructions.

[JadedC36]

Hobit;
Did you misstype 2.8 GHz? Intel does not yet indicate on their web site that a 2.8 GHz is available. However, maybe their site is behind, as it does not list a 0.13 micron size for the 2.0, 1.9 etc!, or a 2.4 GHz, which I believe has been released.

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Mike

[Hobit]

iisbob,hiredgoonz,

OK, the speed in MHz of the CPU is set by processor manufacturer and the chipset on motherboard determines what FSB speed is supported which is in turn selected either by bios, dip-switch, or jumper settings, except that:

A P4 running at 2.0 GHz as specified by Intel = 133 FSB
And
If I either by increasing core voltage or using a different multiplier increase the same P4 to, for example, 2.2 GHz isn’t there a corresponding increase in FSB? (For that matter also the PCI and AGP busses.)


JadedC36
No, Intel does currently market a 2.8 GHz processor, I was just using it as an example. However, implicit in my original question and subsequently confirmed by others responses: when Intel started producing P4s with the Northwood core (and after their production process was perfected) they were producing at least some percentage of P4 CPUs capable of at least 2.8 GHz.

I believe it was Toms Hardware that had a vendor selected P4 that was running stable at 3.0 GHz.

hobit



[This message has been edited by Hobit (edited 01-25-2002).]

[hiredgoonz]

Ok, just so we're all clear on this point: the core clock speed of a CPU is determined by multiplying the FSB by the multiplier...

The multiplier on the P4 is not changeable...the only way to overclock it is to raise the FSB...changing the voltage alone does not overclock the chip, but can aid in maintaining stability when overclocking...

Yes, when you change the fsb, you change the PCI and AGP clock frequencies...these frequencies are determined by a divider which is dependent on the FSB of the system...

For example: on a P2 266 with 66Mhz fsb, the PCI divider is 1/2 and the AGP divider is 1/1, which gives you 33mhz for PCI and 66Mhz for AGP, on an Athlon Classic 850 with a 100mhz fsb, the PCI divider is 1/3 and AGP is 2/3...

On other chips, you can change the multiplier which has no effect on the fsb...an unlocked Athlon will allow you to select any multiplier (within the limits of the chip) but this change is totally separate from the FSB...

There are currently several chipsets available for the P4: SDRAM, DDR and RDRAM, all of which support different FSB speeds, but ultimately, it comes back to the fact that the speed of the chip is based on FSB X Multiplier...

The only difference between a chip sold as a 2.2 and one that will eventually be sold as a 2.4 may be the Multiplier set by Intel at the factory...

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When all else fails, read the instructions.

[iisbob]

Umm, what Hired said. http://www.PCGuide.com/ubb/smile.gif

Can't improve his statement of the facts.

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iisbob

CPU= 5mhz
Memory= 16 K
Storage=10.2MB's
Video=Onboard S3 4K
Modem=14.4 baud
Sound=ISA Yamaha 8bit
Mouse=2 button MS
Monitor=ACER 12.5"
OS= WIN 3.1

My ultimate gaming system :)

[Hobit]

Issbob, hiredgoonz,

Much thanks gentlemen for your good-hearted perseverance. I’ve got it, finally.

"... the Multiplier set by Intel at the factory..."

It is curious that some hacker hasn’t figured out how to do this?

hobit


[This message has been edited by Hobit (edited 01-26-2002).]

[hiredgoonz]

To paraphrase from tomshardware: the multiplier is fixed (burned into special SRAM registries of the CPU) as has been the practice since the Coppermine core of the P3...

The multipliers have been locked on Intel cpus since the 100mhz fsb P2s, although with these, some clever fellow discovered that by covering up one of the contacts on the cpu (where it plugs into the slot) with a non-conductive material, you could unlock them also...then by covering other contacts, you could change the voltage...this is tricky to say the least...

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When all else fails, read the instructions.

[This message has been edited by hiredgoonz (edited 01-26-2002).]