Gulp! We've Set XP Mobile vCore Wrong All This Time!

[Quentin]

It appears we're wrong assuming vCore settings in the BIOS for desktop CPUs translate properly for XP Mobiles! In fact we need to use this simplified table below.

IE: to set a mobile XP to 1.6 volts the BIOS must be set to 1.65. If you set the BIOS to 1.6 the mobile actually would have a vCore of 1.5!

Look what happens if you set the BIOS to 1.85 - the mobile is at 2.0v! And if you set the BIOS to 1.525 the mobile is at 1.35. Forget running it at 1.45 in the BIOS, the mobile would be starved for volts at 1.275.

No wonder so many people have reported XP mobiles run real cool at low voltages but when you crank up the vCore they get RED HOT! (And all these volt mods to get more vCore were unnecessary if you have a mobile.)

Anybody have more info on this?

BIOS vCore. / . Actual
Setting for / . vCore of the
DesktopXP . / . XP-Mobile CPU

1.850 <=======> 2.000
1.825 <=======> 1.950
1.800 <=======> 1.900
1.775 <=======> 1.850
1.750 <=======> 1.800
1.725 <=======> 1.750
1.700 <=======> 1.700
1.675 <=======> 1.650
1.650 <=======> 1.600
1.625 <=======> 1.550
1.600 <=======> 1.500
1.575 <=======> 1.450
1.550 <=======> 1.400
1.525 <=======> 1.350
1.500 <=======> 1.300
1.475 <=======> - N/A
1.450 <=======> 1.275
1.425 <=======> 1.250
1.400 <=======> 1.225
1.375 <=======> 1.200
1.350 <=======> 1.175
1.325 <=======> 1.150
1.300 <=======> 1.125
1.275 <=======> 1.100
1.250 <=======> 1.075
1.225 <=======> 1.050
1.200 <=======> 1.025
1.175 <=======> 1.000
1.150 <=======> 0.975
1.125 <=======> 0.950
1.100 <=======> 0.925


This comes from a thread over at aoaforums:
http://www.aoaforums.com/forum/showthread.php?t=30322

And the full VID/VCC_CORE table can be seen at:
http://fab51.com/cpu/barton/athlon-e20.html

 

[chinkgai]

mine seemed like they were right in my abit nf7-s

the temperature seemed to scale correctly as voltage was increased too

 

[maluckey]

And to think that I used to run at 1.9v set in BIOS. No wonder I had difficulty keeping it cool!!

 

[Quentin]

Yeah, this is looking more and more like a bum steer, but an interesting one. Surely somebody would have figured this out a long time ago if it were true.

But for fun - if we were to extrapolate from the table (following the pattern in the upper half of the table) we'd get these figures. Pretty darn hot!


2.000 <=======> 2.300
1.975 <=======> 2.250
1.950 <=======> 2.200
1.925 <=======> 2.150
1.900 <=======> 2.100
1.875 <=======> 2.050

Above figures extrapolated from below:

1.850 <=======> 2.000
1.825 <=======> 1.950
1.800 <=======> 1.900
1.775 <=======> 1.850
1.750 <=======> 1.800
1.725 <=======> 1.750
1.700 <=======> 1.700
1.675 <=======> 1.650
1.650 <=======> 1.600
1.625 <=======> 1.550
1.600 <=======> 1.500
1.575 <=======> 1.450
1.550 <=======> 1.400
1.525 <=======> 1.350 (Stopped here since this is the lowest vCore for a Socket A XP-M)

 

[Duvie]

I wonder how many killed the chip from this...

 

[Hyperlite]

that is indeed interesting...

 

[TRUMPHENT]

My previous mainboard was a Soyo Dragon Ultra Plus Edition. It shipped from CompGeeks with the Mobile processor Bios. I flashed it back to the one for standard XP's since I didn't own a mobile cpu.

This may have caught others unawares by installing a mobile processor in a mainboard without a suitable BIOS. That may explain why Soyo released a special BIOS for the mobile processor on my old mainboard.

Hmm, the things the manufacturers don't and won't tell you.!

 

[Fern]

Nice find Quentin :thumbsup:

This does look legit. If confirmed, we need some modded BIOS from TICTAC or someone.

Fern

 

[Munky]

Is there a way to read the actual voltage without using a multimeter? My motherboard has a voltage monitor, and there are windoze utilities that do it as well. I have a mobile barton, and all apps/bios report the voltage that I set it at: 1.78v. My mobo is an Abit AN7, and even with the latest bios, it still does not recognize a mobile processor, whereas my old Asus a7v333 did see it correctly (by the name string I mean). Does that make any difference to the voltage being used?

 

[Fern]

Hey,

Is this a problem ONLY with the A7N8X mobo's? Or all mobo's?

 

[Quentin]

Originally posted by: Fern
Hey,

Is this a problem ONLY with the A7N8X mobo's? Or all mobo's?

Fern, this is looking like a false alarm. Sorry to cause such a fuss but when I saw this last night it looked real. Anyway, this wasn't specific to any motherboard.

 

[Hyperlite]

?

 

[Avalon]

I blame Asus
Can't say that I noticed such irregularities with my chips on my Epox 8RDA3i.

 

[Tiorapatea]

I am running my XP-M at 1.475V on an Abit NF7S Rev2. So what does N/A mean?!