RE: [cobalt-users] 450/475Mhz CPU upgrade

["Jerry Farquhar" <jerry@xxxxxxxxxxx>]

You mentioned having a Qube over clocked??

Qube2 or Qube3??

If it's a Qube2.. please share the down and dirty on what you did to over
clock or upgrade the CPU.  I've got a couple of perfectly good barely ever
used Qube2's just sitting on the shelf with nothing to do..

Jerry

-----Original Message-----
From: cobalt-users-admin@xxxxxxxxxxxxxxx
[mailto:cobalt-users-admin@xxxxxxxxxxxxxxx]On Behalf Of jim st john
Sent: Tuesday, January 07, 2003 7:57 PM
To: cobalt-users@xxxxxxxxxxxxxxx
Subject: RE: [cobalt-users] 450/475Mhz CPU upgrade


All reasonably-current versions of the AMD K6-2 CPU operate with a 100
mhz bus speed.  There are a couple of oddball exceptions.  All Raq3s and
Raq4s operate at a 100 mhz bus speed.  Increasing processor speed by
tweaking the bus speed is most definitely not recommended.

The final operating speed of the CPU is the bus speed times a
multiplier.  On the K6 CPU, there are 3 pins that are used to select the
multiplier, thus 8 possible values (000-111) producing multipliers
ranging from 2.0 to 5.5 in steps of 0.5.   The faster-rated CPUs operate
over a wider range of multipliers, but simply changing a 300mhz CPU for
a 450 or 500 mhz CPU won't produce a speed improvement unless you also
change the multiplier.

On the Raq3 models, the multiplier pins are set to: 101, a multiplier
value of 3, for a 100x3=300 mhz cpu speed.

On the Raq4 motherboards, the multiplier pins are set to: 000, a
multiplier value of 4.5 resulting in a processor speed of 450 mhz.

The published jumper modification to the Raq3 motherboards simply
grounds the 'first' multiplier pin, changing the multiplier from 101 to
001, multiplying by 5.0, yielding a cpu speed of 500mhz.  Note that this
is in no way considered 'overclocking', as long as the CPU is rated for
500 mhz.

Regarding Bruce's comments regarding instability above 450mhz, possibly
this problem has been fixed in recent versions of the K6 cpu.  I have 2
Raqs and a Qube operating at 500mhz and haven't seen any problems.

If you are concerned about this, then another jumper could be added to
bring the multiplier down to 4.5 as is done with the stock Raq4 boxes.

As mentioned in a prior post, the faster CPU speed produces more loading
on the power supply and results in additional heat that must be
dissipated.  This can be a significant amount of added heat when the CPU
is heavily loaded.  The stock Raq3 heat sink is marginal for operating
at 500 mhz.  As a minimum make SURE that you use heat sink compound
between the CPU and the heat sink.  For use in a warm environment I
would strongly recommend either a physically larger heat sink or one
with fan cooling.  Because of the 1-U form factor, you need a
specially-designed cooling fan that resembles a small sideways turbine
blower.  A normal heat sink fan would be totally blocked by the cover
and wouldn't move much air.

Keep an eye on the CPU temperature, particularly when the CPU is loaded.

-jim-


On Mon, 6 Jan 2003, Bruce Timberlake wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> > Bruce, sorry to disagree but I believe you're wrong here. If you
> > drop in a 450/475 it will run at 300MHz as the socket is set to
> > 3x100. You must jump pins in the CPU socket to get 5x100.
>
> Hm. I'm sure you're right, but I had an ISP customer who was
> converting all their RaQ 3 to RaQ 4, and I _thought_ all they were
> doing was dropping in a 450 and OS Restoring with the RaQ 4 CD...
> that's all they _said_ they were doing anyway...
>
> I've got a RaQ 3 kicking around that I'll drop a RaQ 4 CPU into and
> see what happens...
>
> - --
> Bruce Timberlake
> 
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.1 (GNU/Linux)
>
> iD8DBQE+Gi2FvLA2hUZ9kgwRAnAhAJsGyWSb3vLY/sSAukEanDpGArTOaACfYAk9
> tyWSEM81qBQ1w7disgtoL/0=
> =hy83
> -----END PGP SIGNATURE-----
>
> _____________________________________
> cobalt-users mailing list
> cobalt-users@xxxxxxxxxxxxxxx
> To subscribe/unsubscribe, or to SEARCH THE ARCHIVES, go to:
> http://list.cobalt.com/mailman/listinfo/cobalt-users
>

_____________________________________
cobalt-users mailing list
cobalt-users@xxxxxxxxxxxxxxx
To subscribe/unsubscribe, or to SEARCH THE ARCHIVES, go to:
http://list.cobalt.com/mailman/listinfo/cobalt-users

_____________________________________
cobalt-users mailing list
cobalt-users@xxxxxxxxxxxxxxx
To subscribe/unsubscribe, or to SEARCH THE ARCHIVES, go to:
http://list.cobalt.com/mailman/listinfo/cobalt-users

_____________________________________
cobalt-users mailing list
cobalt-users@xxxxxxxxxxxxxxx
To subscribe/unsubscribe, or to SEARCH THE ARCHIVES, go to:
http://list.cobalt.com/mailman/listinfo/cobalt-users