On 8 Oct 99, at 22:54, Ed Estigoy wrote:

> I hope you help me and shed some light regarding this post....
> How do you set for 3V on a motherboard for CPU change from
> an Intel486DX2 to an AMD486DX4.


  If the motherboard offers a 3V setting (most don't ...), there will
be a "jumper" to adjust for this.

  If the motherboard doesn't provide this, you may still be able to
find a voltage regulator module that mounts between the CPU and the
socket.  Note that when these were common, they were often priced at
$50-60, so this may not be cost-effective compared to buying a new
motherboard.

  [The Intel DX4, in its OverDrive form, included the voltage
regulator built into the CPU package.  But (a) AMD never released a
similar package, and (b) this was about $50 more expensive than the
stock DX4....]

> Do they differ in  voltage requirements ?

  Yes.  All DX4 and above used 3v; only the Intel OverDrive was
intended to run in a 5v-only motherboard.

> How do you figure out the current CPU voltage in use, say for the
> DX2, on the board. Are there any test points where you can place
> voltmeter test leads ?

  There are pins of the CPU socket that provide Vcc and ground.  But
unless the board provides a choice, it must be trying to supply 5v.

> The computer is an acer,  is it compatible with AMD cpu chip.
> I've tried to directly replace the DX2 chip with the DX4 but the
> system only reports it as a 33Mhz ! afterwards,the system just
> hangs / freezes ( I'm afraid that I've fried it )
> But when I place back the DX2 chip, the computer goes into its
> normal routine : system readout as 50Mhz, until it goes to
> normal displays / mode.
>
> the motherboard has a series of numbers on it :
> 55.41301.0514066422G S.
> On the underside of the case,
> model no    : P440DB
> extension   : 4444LB
> FCC ID      : GQ81D2P  A1
> Current CPU : 486DX2

  The FCC ID confirms that this is an Acer board, although I can't
find one with this suffix on the FCC's site.  Acer's support site
indicates that this is probably using their "A1" motherboard, but
they have no info about it on-line.  Nor is it listed at

http://members.xoom.com/WEB_HQ/boards.html

  Without more info, it's impossible to tell whether adding a voltage
regulator is going to be sufficient to support your AMD CPU; I
suspect not.

David G






> Diagnostic run reports it as :
> computer type      : AT clone  ....oh dear me !!!
> submodel           : PC-AT
> model/submodel/rev : FC / 01 / 00
>
> thanks in advance,
> Ed
>
> PS:
> I don't have its manual.
>
>                 Curious about the people moderating your
>                    messages? Visit our staff web site:
>                      http://nospin.com/pc/staff.html
>

         PCBUILD maintains hundreds of useful files for download
                     visit our download web page at:
                     http://nospin.com/pc/files.html