PIII on a PII mb

Don't ask how to over-clock.
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andrea
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Hi, I'm Italian so i'm sorry for my bad English.
I've an ABIT LX6 mb, which was PII 266Mhz slot 1 equipped until last week.
Now I'v try to upgrade the system to a "new" PIII cpu (PIII 450/100/512/2.0 on slot 1).Before proceding, I thought a bit about multiplier factor and system bus frequency.
In the past it run at 66mhz x 4 to drive the PII 266: now it should run, if mathemathic isn't a opinion, at 100mhz x 4.5 to drive the PIII 450,doesnt'it?
So i flashed the bios with last BIN from ABIT to ensure more compatibility with new hardware and tryed to upgrade the system.
Surprising me, now it shows me a PII 400Mhz instead of PIII 450 (and this is only a CPU name problem, i think, and it isn't a drama) but it runs at 90,3...x 4!!!!! I tryed other configuration (no more jumpers in my life, fortunately!), but the CPU was not recognized correctly and the BIOS did reset it to PII 233 which is the lower type. Now it runs 90,3..x 4 driving my PIII 450 at 400Mhz. How can i get full power from it? And 100Mhz FSB instead 90,3 (75, 83 etc. are quite normal in the world, but 90,3? I've never heard about this!)?
Anyone can help me?
Thanks a lot
soupy
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Officially, this is only a 66Mhz FSB (ie Celeron) board, which means a PIII with 100Mhz FSB will not run at full speed. I couldn't find anything to suggest that the SoftMenu will allow a 100Mhz FSB, and the FAQ says it won't.

Can the Pentium II 350MHz CPU work fine under every external clock speed with the LX6?

It can work fine with external clock speeds of 66, 75 & 83 MHz, but not 100MHz.

http://fae.abit.com.tw/eng/faq/mb/lx6.htm

http://fae.abit.com.tw/eng/download/bios/lx6.htm
Flash your BIOS at your own risk.
andrea
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Joined: Fri May 02, 2003 4:13 pm

First of all, thank you very much for your help!!
Well, LX6 motherboard supports natively 66Mhz FSB (75 & 83 for overclocking purpose, I suppose): so I can install CPU until 300Mhz.
But, upgrading BIOS with the most recent ROM from Abit (original BIN file), now I can choose from 66, 75, 83 AND 100Mhz. Before upgrading BIOS, there wasn't the 100Mhz option to choose. Why, now, a 100Mhz FSB option is present? Can LX6 really drive a 100Mhz FSB?
Beyond this, now I can choose from new CPU standard types (automatic FSB & multiplier settings), from PII233 to PII350Mhz.
In theory, you can obtain 350Mhz only manually from a 100Mhz FSb and x3.5 multiplier. In the same way, you should obtain a a 450Mhz (a PIII CPU) from 100Mhz FSB with x4.5 multiplier.
So, I set a 100Mhz FSB and x4.5 multiplier to obtain 450Mhz; I disabled CPU Error messages on POST and I installed the OS. From MSINFO I could notice the CPU was driven at 90.3Mhz FSB with x4.5 multiplier, giving about 400Mhz.
Is a 90,3Mhz FSB a kind of motherboard overclock or a downgrade of 100Mhz FSB for stability purpose? Why when I MANUALLY set 100Mhz x4.5, it's automatically reduced to 90.3Mhz? Can the PIII450 CPU have a locked multiplier factor (x4.5?)?
Anyone can rescue me from this hell?????
soupy
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The PIIIs are multiplier locked, yes.

If your CPU is saying it's running at ~400Mhz, then it would seem it's set to 90.5 x 4.5 = 406.3. 100Mhz really isn't 100Mhz on this board.

Also, the LX is only capable of dividing PCI speeds by 1/2 of FSB, so at anything over 66MHZ FSB you're overclocking the hell out of your peripherals.

I'd give up on 100FSB and look for a 533 Celeron, or MAYBE a PIII-800 running at 533.

http://groups.google.ca/groups?selm=3bc ... put=gplain
Flash your BIOS at your own risk.
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