HP 8750C CPU Upgrade Advice

Don't ask how to over-clock.
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KachiWachi
The New Guy
Posts: 1451
Joined: Fri Mar 29, 2002 10:32 pm
Location: Pennsylvania, USA

Hi All!!

I'm finally going to upgrade my girlfriend's son's computer with a new CPU to fix the "freezing" problem noted with this particular unit (MEW-AM motherboard, Socket 370).

I currently have the v2.06 BIOS installed, though the last release was v2.10. I've heard that v2.06 was more stable, so that's why it was installed at a previous "service". In v2.07 they added CPU support, removed some features (SMART monitoring 200msec) and also "zero the first 8MB of extended memory"...not sure what this means. In v2.08 they added B stepping for 933 and 1GHz CPU's. In v2.09 they removed IO APIC support. In v2.10 they added more CPU support again (10/11X multipliers).

Currently he has a PIII 667MHz SL3VK (stepping cA2, 0681h, 667/133, 256 L2). For this board not to hang, a 100MHz bus CPU is required. (So they tell me anyway... :roll: I tried the PCI video card trick...it stays up longer, but still freezes.)

I'm looking for an 068h, cC0 stepping PIII, which could go as high as 900 with a 100MHz bus. Support for cC0 was introduced in the v2.02 BIOS, so this should work fine. (<-- I think...????)

I have recently seen a 068Ah, cD0 stepping CPU that may work, but from what I gather from the BIOS list, this stepping was added in the v2.07 BIOS.

If I try to install this using the v2.06 BIOS, it won't work...correct??

Will a Tualatin (tA1, tB1) work in this board? v2.10 BIOS says added "new Pentium III B step microcode"...whatever that means????

Any thoughts/advice would be appriciated. Thanks!!
KachiWachi
The New Guy
Posts: 1451
Joined: Fri Mar 29, 2002 10:32 pm
Location: Pennsylvania, USA

I'm wondering if the v2.06 BIOS can be patched with the applerom patcher to support the newer CPU's without removing the stuff that HP removed.

I can supply the file if a moderator can try the patch...
Rainbow
The UniFlasher
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That patcher is freely available so you can try it.
Patched and tested BIOSes are at http://wims.rainbow-software.org
UniFlash - Flash anything anywhere
KachiWachi
The New Guy
Posts: 1451
Joined: Fri Mar 29, 2002 10:32 pm
Location: Pennsylvania, USA

I know Rainbow...just though that you all have had more experience with his patcher and what it can/can't do.

I'd only be interested in adding whatever microcodes would be needed to support the higher Multiplier PIII's to stepping cD0, leaving everything else intact. Seems a cC0 is very hard to find...even though it really isn't that old...

Maybe applerom will chime in at some point...
woolfman2
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An alternative would be to see if the Intel Microcode Update Utility (Checkup6) is compatable with the existing BIOS. I have successfully used this utility to add microcode support to both Award and AMI bios that previously lacked them. The key is that the BIOS needs to already have CPUID support for a given type of CPU. CPUID support and microcode support for a particular stepping are two different issues. Be aware, however, since this is an OEM board with an OEM bios, that neither the Apple_Rom patcher or the update utility may work. At least, the Intel Update Utility will say that it is not compatable and will not even try to write to your BIOS.
KachiWachi
The New Guy
Posts: 1451
Joined: Fri Mar 29, 2002 10:32 pm
Location: Pennsylvania, USA

I thought of another alternative that I wonder if anyone has tried yet.

The motherboard BIOS auto-senses the installed CPU and sets the bus and multiplier accordingly. What if I somehow was able to disable certain pins on the clock chip...letting it think it was running at the 133MHz setting, but was really only running at 100MHz?

The board uses an ICS 9250AF-23 clock chip, for which I downloaded the .pdf datasheet for (if you ask for it manually, the ICS server will give it to you...it just isn't highlighted as a current link).

I have to do a bit of reading now, but do you think this might be possible? The motherboard does have pads where I could manually install jumper wires for FS0->4. How will the BIOS react to this? Is there some sort of auto-correcting that may happen, or might it be as simple as just lifting/grounding a pin?

Thanks for your thoughts.
KachiWachi
The New Guy
Posts: 1451
Joined: Fri Mar 29, 2002 10:32 pm
Location: Pennsylvania, USA

Just found out it is a no-can-do, since some of the pins provide dual duty (rats!!).

It almost seems that for this board, they used a different clock chip that made things go faster, as the chart on the motherboard doesn't match what the chip does when configured as such.

Can anyone tell me briefly, after the BIOS reads the CPU characteristics, how the thing sets up the clock chip? I know from reading that the clock chip will read the FS0->4 at power-up, and this will set up the clocks...but what happens prior to that? What sort of chips are involved between the BIOS chip and the clock?

Thanks again.
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