David Maynard wrote:
~misfit~ wrote:

I'm running a Tualatin Celeron 1.3Ghz in a Gigabyte GA-6VEM-L
integrated mobo. It doesn't have BOIS setting to change between
66/100/133, or switches/jumpers from what I can see. It seems to get
the default FSB speed from the CPU and it then allows you a certain
overclock (in BIOS) from there, in pre-determined steps
unfortunately, I can't go one Mhz at a time. Well, my 1.3 is running
24/7, Prime95-stable at 124Mhz FSB for 1.612Ghz. I'm pleased with
that, it has a copper-bottomed HSF on it that came with a Barton and
stays cool, Also I removed the IHS so the die is in direct contact
with the HS. There is no way in BIOS to adjust vcore, however this
CPU has always ran a little high, 1.53 average according to MBM5,
ranging between 1.51v and 1.54v. (Strange because I had a Celly
1.4Ghz in this board last week and it only ran at 1.35vcore. It ran
fine though, however I didn't try to OC it at that low a vcore. Both
have 1.5v written on them)

I've noticed odd Vcore values with tualatins on non-tualatin
motherboards
as well but it's not a problem here as I always have something else
setting it.

It's a strange mobo. The manual claims it supports "all new Pentium III
processors (FC-PGA & FC-PGA2 package) and Celeron processors in FC-PGA
package. Supports 66/100/133Mhz system bus"

Note it doesn't say anything about FC-PGA2 (Tualatin) Celerons. However it
is running the last BIOS release (F8).

The tualatins using an open drain FET to set the Vcore identification
pins whereas the earlier celerons used straight wire shorts to
ground. And the specs for earlier tualatins specify the motherboard
pull up to be 10K, or more, while the tualatin says 1K. I could
imagine that the 10K "or more" pull-up on the non tualatin
motherboards is not always sufficient to drive the pin high when it's
not being pulled low by the on-board FET.

Which would be a great theory except for not explaining why yours
seem to
be 'high' instead of low, as that theory would expect. Unless the
on-die
FET pull downs depend on some Vss pin that's 'unused' on earlier
motherboards.

Whatever the reason, I've seen it too.

Thanks for the explaination.

Now, 1.61Ghz is pretty damn good I figure. (Even though it's a
dreaded Via chipset board I get 107 marks with CPUMark99, up from
84.9 at 100Mhz FSB). From what I can tell I can't monitor die-temp
with this board. However socket temp sits at around 29°C, case temp
19°C, crunching SETI full-time, about the same as the 1.4 did using
it's stock HSF. It's winter here.

I'm never satisfied with an OC until I've reached the point where I
get errors in Prime, then backed off to my last stable setting. I
can't do that with this set up as-is. Also the PCI bus is 41Mhz, a
setting I'm not exactly comfortable with although all seems fine.
The only card I have in it is an Adaptec AHA-2940-AU for my old
scanner and it's always been a forgiving card bus-speed-wise,
everything else is on-board. (I haven't tried my scanner at this
speed though). The HDD is an old 8.4GB Fujitsu. The board actually
has three bulging capacitors, with two of them leaking a little on
top. I have replacements ordered and they should be here in a few
days. I was going to replace them as soon as they arrived, however,
with it running this well I might just leave them as they are until
I *have* to replace them (unless I'm risking my CPU?)

So, the question: Can I easilly (and non-destructively in case I
need to revert back) fool my mobo into thinking it's a 133Mhz FSB
CPU? It does run 133FSB CPUs. That way I could try for 1.73Ghz and
have the PCI back in spec. I realise that there isn't a very good
chance of me getting it to run at that speed (especially with no
vcore adjustment) but this *does* seem to be a good bit of silicon,
I'd hate to not try it. I'm sure most of you understand.

Unlikely you're going to get there, especially without a Vcore
increase,
but who knows? It's already doing better than average to be stable at
1.6
Gig at stock Vcore.

I figured that but it doesn't hurt to try, or ask opinions. :-)

Can it be easilly done?

Unfortunately, no. The bus select pins are pulled high on the
motherboard with pull downs on the processor to select which speed it
wants and to get 133MHz as the 'requested' FSB you need to break the
pull-down on BSEL1 (AJ31) so that it goes high (on the VRM side). The
obvious way is to break the pin, but that isn't replaceable (for most
mere mortals anyway). The alternate is to insulate it somehow.

I have re-soldered a pin back on a Coppermine Celeron once, still have the
CPU, still going strong and it's been in and out of sockets a few times.
However, that was an 'outside' pin, I doubt I could do it with a pin in the
middle of a bunch of other pins.

Vcore, btw, can be increased by jumpering processor pins to Vss. You
don't have the choice of just any voltage because you can't make a
pin go 'high' with that method but, with a 1.5 volt default Vcore,
you can get 1.55, 1.6 and 1.65. The next higher jump, by only
jumpering to Vss, is to 1.9.

The really ambitious have been known to break the motherboard traces
to the socket and wire in their own DIP switches for the VID and FSB
signals to
make both adjustable.

Heh, more than I'm prepared to do at this stage.

Thanks David, I'll probably leave it as it is. I'm just running Prime95 on
it again. I tested it for five hours before and it was fine. However, it
seems to have gone through a lot more SETI/BOINC units than it should have
since I last checked the status so I'm wondering if it's tripping up
somewhere. Unfortunately with BOINC I don't seem to be able to find a log
like I had with SETISpy to allow me to look back over WU history, once it's
communicated with the server it clears the 'WU done' tab on the client.

Cheers,
--
~misfit~