CPU thermal properties vary by SPEC? How to specify SPEC?

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soundOFsilence
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CPU thermal properties vary by SPEC? How to specify SPEC?

Post by soundOFsilence » Tue Jul 08, 2003 1:52 pm

I have been researching thermal properties of various CPUs. For example, there are 8 different spec versions on the Pentium 4 1.6A chip:


SL6BC 1.60 GHZ BOX 400 MHz 478 pin PPGA FC-PGA2
SL679 1.60 GHZ BOTH 400 MHz 478 pin PPGA FC-PGA2
SL668 1.60 GHZ BOX 400 MHz 478 pin PPGA FC-PGA2
SL62S 1.60 GHZ OEM 400 MHz 478 pin PPGA FC-PGA2
SL5VH 1.60 GHZ BOTH 400 MHz 478 pin PPGA FC-PGA2
SL5UW 1.60 GHZ BOX 400 MHz 478 pin PPGA FC-PGA2
SL5US 1.60 GHZ OEM 400 MHz 478 pin PPGA FC-PGA2
SL5UJ 1.60 GHZ BOX 400 MHz 478 pin PPGA FC-PGA2

see http://processorfinder.intel.com/scripts/default.asp

The "thermal guideline" for these CPus vary from 38watts (SL62S) to 60.8watts. What exactly is "thermal guideline" and "thermal spec"? Is this the amount of thermal heat generated(under what load?)?

So should(could) one look for specific spec values for Intel chips when ordering a new CPU?

A somewhat related question, can one install a P4 Mobile (M) chip on any socket 478 Motherboard?

Thanks...

Jan Kivar
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Post by Jan Kivar » Wed Jul 09, 2003 12:10 am

Well, the biggest difference between these processors is that some are Williamette core (0.18 micron) and some are Northwood core (0.13 micron). Northwood cores run a bit cooler. From the given list only SL668 and SL62S are Northwood.

Northwood cores use much lower voltage, thus lowering the wattage. SL668 uses .025V higher VCore than SL62S, which explains the difference between the wattage for these two (maybe...). [I wonder what the wattage would be for the Williamettes, if the VCore was dropped to 1.5V...]

Seems that the "thermal guideline" is for OEMs to plan what cooler they would have to use, or for HS makers to test/rate their products/designs.

IIRC "thermal spec" is the maximum core temp before the integrated throttling feature kicks in, to prevent the processor from burning itself.

Yes, You should look for certain sSpec when You buy a processor. There are only two kinds of Northwoods (ATM), and the other is marked "BOX" and the other "OEM". This means (most likely...) that if You buy a "boxed" version (comes with Intel retail HSF) You'll get a SL668, or if You buy just the processor, You'll get a SL62S.

I'm not sure if the Intel marked "oems" are used only by Dell etc., and cannot be bought separately. I don't know either if one could buy a PIV without the retail HSF, so maybe the only version You can get is the SL668. You could probably undervolt to obtain the same wattage that SL62S has. (as the processors have same core stepping)

I don't know about the installation possibilities of a Mobile version. Use the search feature, this has been discussed before.

Cheers,

Jan

soundOFsilence
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Location: San Francisco, CA

Post by soundOFsilence » Wed Jul 09, 2003 7:23 am

Jan, thanks for clearing that up. I realize now that many of these CPUs are not "1.6a" after all, they appear to be plain "1.6".

But... even between the box and the OEM version, there is quite a bit of difference. Box (SL62S) has thermal guideline at 38W, OEM (SL668) has it at 46.8W. So, should we prefer the boxed retail version, and throw away the HSF, or is the difference because it is a CPU with HSF, and that changes the thermal guideline maybe?

Wedge
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Post by Wedge » Wed Jul 09, 2003 8:55 am

My heat spreader has 1.7 on it. What should I look for to determine if this is Northwood or Williamette. It was given to me so I have no idea how it was packaged.

Jan Kivar
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Post by Jan Kivar » Thu Jul 10, 2003 2:52 am

soundOFsilence wrote:Jan, thanks for clearing that up. I realize now that many of these CPUs are not "1.6a" after all, they appear to be plain "1.6".

But... even between the box and the OEM version, there is quite a bit of difference. Box (SL62S) has thermal guideline at 38W, OEM (SL668) has it at 46.8W. So, should we prefer the boxed retail version, and throw away the HSF, or is the difference because it is a CPU with HSF, and that changes the thermal guideline maybe?
Some of the difference is caused by the different voltages, but I'd have to say that it shouldn't make such a big difference per se. I found this here:
The low wattage Pentium 4 Northwood chips are intended for small form factor systems and are limited to less than 45W maximum power output
So it would seem that the SL62S is sent only to OEMs. Maybe some vendors sell the low wattage models...

Cheers,

Jan

Jan Kivar
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Post by Jan Kivar » Thu Jul 10, 2003 3:18 am

Wedge wrote:My heat spreader has 1.7 on it. What should I look for to determine if this is Northwood or Williamette. It was given to me so I have no idea how it was packaged.
If You have the processor uninstalled, just find the 5-symbol code on the top of the die, or from the sticker, if the processor has one. If You have the processor installed in your system, You can't really get the exact info fom the processor (as there is no way to read the sSpec code from the CPU). You can use the link that soundOFsilence posted in the first post, just select the appropriate core & bus speed and the package type, and You should end up with just a few possible ones. Most of the processors have the same thermal power & voltage, sSpec code can be also used (IIRC) to identify at which factory the processor was made, thus same specs for different sSpecs.

If You just want to know whether your processor is either Williamette or Northwood, You should use WCPUID or CPU-Z, and look for the L2 cache size. Williamettes have 256 kB, whereas Northwoods have 512 kB. Some BIOS' also show the cache size, either in the BIOS itself, or at the screen that is shown just before the OS starts to load.

Cheers,

Jan

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