Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Thank you Paul for the very detailed response. Both the motherboard and
cpu are new. I have not performed any modifications to the board and the
vcore reading is taken from the hardware monitor in the bios. This is
the only quirk I've had with my setup. My cpu is a 2.4c that I bpought
to do some mild overclocking. Running it at its default settings set the
vcore to 1.6v. When I tried to overclock the cpu I left the vcore
setting on 'auto' and my attempts to overclock were met with a
non-functioning computer. Many cmos clears later I figured out that to
achieve a 5:4 memory divider for a 250fsb I had to set the memory speed
to 320. Now the cpu is running at 3.0GHz and the memory at DDR400. And
the vcore..........1.6v. As for the vid cmos setting I'm leaving it set
to '62'. Any ideas as to what the consequences might be if the setting
is changed?
Richard
Paul wrote:
> In article <PKH5d.85296$Kt5.29657@twister.nyroc.rr.com>, Richard
> <boetard@hotmail.com> wrote:
>
>
>>I have a P4P800se with a retail 2.4c P4 cpu. The vcore seems to be stuck
>>at 1.6v. No matter what the cpu voltage is set at the board reads 1.6v.
>>What gives?
>>Another question regarding 'vid cmos setting' in the bios. What is this?
>>Mine is set to '62'. Does this have any bearing on the vcore?
>>Thanks
>
>
> I've been looking at your question since your first post, and
> am no closer to coming up with a theory as to why it is doing that.
>
> The "VID cmos" is a most curious setting. It appears next to the
> multiplier setting section, implying the VID cmos thing has something
> to do with ES (engineering sample) unlocked P4 processors. Since ES
> processors don't have a spec that I've ever seen, it is hard to
> guess why this setting is necessary, when there is a very nice
> Vcore setting option elsewhere in the BIOS. There are only a
> couple of posts on Abxzone about it, and that is where I
> read about this speculation, that it is related to ES processors.
>
> There are two power specs for Pentium processors. The ones I've got
> are VRM 9 (5 bit VID code) and VRD 10.0 (6 bit VID code, socket 478).
> There is a VRD 10.1 spec, but it is for the LGA775 socket.
>
>
http://www.intel.com/design/pentium4/guides/24920504.pdf (VRM9)
>
ftp://download.intel.com/design/Pentium4/guides/25288503.pdf (VRD10.0)
>
> The reason I identified these two specs, is many Asus boards can take
> two kinds of processors that correspond to those two specs. The first
> spec handles voltages from 1.1 to 1.85V, and that was used for early
> Pentium processors (1.75V being a typical value). Later processors
> use the 0.8375 to 1.6V spec. Apparently, a pin called BOOTSELECT
> on the later processors, can be used to tell whether the former
> or latter spec is required. Page 22 of this Vreg spec shows an
> example of a dual spec regulator circuit, using the BOOTSELECT pin.
>
>
http://www.analog.com/UploadedFiles/Data_Sheets/85022276ADP3181_prg.pdf
>
> Now, the value "62" appears to be decimal, for the bit pattern 111110.
> That is a 6 bit code, presumably corresponding to a VID code for a
> VRD 10.0 processor. But the value 62, when you look it up in the spec,
> does not correspond to a "useful" value. It would give 1.1V to a
> processor, which would likely cause it to fail to boot. The value
> 42, a bit pattern of 101010, gives 1.6V.
>
> What other things do we know ? Asus doesn't like to allow users
> to undervolt processors. Generally, overvolting is prevented by
> Asus, by limiting the hardware to a safe value. 1.6V is the highest
> value that a VRD 10.1 processor can get.
>
> The absolute max voltages for the 1.6 and 1.85 volt processors are
> 1.75 and 2.1 volts. So, your setting problem doesn't appear to be
> related to overvolting, as that limit would more likely be 1.75V
> at least.
>
> About the only speculation I can offer, is part of your board
> thinks it has got a VRM 9 processor, but the BIOS checks the
> CPUID register in the processor and decides it is a VRM 10
> processor, and sets the voltage as high as that spec will allow.
>
> Maybe it has something to do with the BOOTSELECT pin malfunctioning
> on the processor, or not making good contact ? Or some other
> aspect of mis-identifying the processor ? Does your board have
> any socket mods or volt mods ? Is it a new board or a used one
> that someone could have modified ?
>
> The 1.6V probably isn't going to hurt anything, as long as the
> 1.75 absolute max isn't being exceeded.
>
> Another question for you - where is the 1.6V being measured ?
> Are you seeing this in the BIOS hardware monitor page or
> are you looking in Asus Probe/MBM5 ? Maybe the voltage you
> are looking at isn't the Vcore, but is some other voltage ?
> There has to be a logical explanation somewhere there, and
> looking at Vcore related issues is making your symptoms
> hard to explain. At least, I haven't been able to cook up
> any half baked theories yet.
>
> HTH,
> Paul
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