Abit BH6 and 866 PIII compatability?

[GristleBear]

Hi,

I'm a new kid on the block and I could use some help.

I've just built my first PC and it actually works! Yeah! The mobo is an Abit BH6 rev1.2. CPU is a 366 Celeron(100) which is overclocked to 550. SDRAM is 3-64MB sticks of Micron 100 ECC. Video is by a Gainward G3 Ti450 Golden Sample. An Adaptec AHA2940UW keeps the 4GB and 23GB SCSI drives under control. Sound will be handled by a Phillips harmonic Edge, after it arrives and is installed. Up front there's a 1.44MB floppy and a 52X IDE CDROM. OS is Windows 98SE.

The problem is this. I'm not satisfied with the 366 Celeron, even though it's overclocking very nicely. I don't believe that it will be powerful enough to handle the video and music chores I have planned for this computer. Toward that end, a good friend has given me an 866 PIII(133) which I have been attempting to get to work in this computer, so far without success.

Therefore, I ask you this. Does anyone know for certain whether I CAN or CANNOT use an 866 PIII(133) in an Abit BH6 rev 1.2 motherboard?

The latest bios from Abit has been flashed successfully to the board's CMOS. This bios is supposed to support up to an 850 PIII(100). The Abit Softmenu CMOS setup allows the FSB to be set to 133, and the correct multipliers are there. AND, since the BH6 is such a good overclocker's mobo, and 866 isn't all that much more than 850, it seems like this should work. Right? Maybe? AND, if the 866 PIII(133) won't work, perhaps because of that little 133 thing, is it just possible that a 1GHz PIII(100) WILL work?

I know that there are at least 3 different buses that have to sync together to make this thing work. The trouble is that I don't really know how to relate them. So, can someone please tell me how the FSB speed relates to the speed of the internal CPU bus AND how the AGP bus relates to both of these?

For instance, does an 866 PIII(133) HAVE TO be run with a 133 FSB setting? THEN, do I need to run my AGP at 2/3 instead of 1/1? (Even though the resultant freq, 133 x 2/3 = 88.7, is NOT a multiple of 33?) AND then there's also the matter of whether my SDRAM and SCSI controller will overclock from 100 to 133. (I really need to run the specs down on all these items.)

So that's it in a nutshell. Any and all help will be deeply appreciated.

Thanks,

Andy Cook

 

[oldfart]

Welcome to Anandtech!

Since you have a rev 1.2, not a 1.0x, you should be ok. The 1.2 does have a 1/4 PCI divisor, the 1.0x does not. You have a 124 MHz FSB option correct? This is one way to tell if you have the 1.2 version. You should have no problem running 133 MHz FSB on that board. Yes a PIII 1 G 133 FSB or 100 FSB will work. The only fly in the ointment is the 2/3 AGP which puts your AGP way out of spec @ 89 MHz. I'm pretty sure the GF3 cards are ok with this, but can't say for sure.

That PC100 will likely be a problem though. It is probably why you cant get it running. You did set the PCI for 1/4?

 

[MadTom]

I have had a ASUS V6600 (GeForce SDR), PINE GF3 Ti200 and PINE GF2 MX400 running with AGP speed of 89 MHz. All worked without flaws. So, NVIDIA should handle the higher AGP speed. It was on a P2B-F, BTW.

And, set AGPCI 2:3 (or if you are happy and have the option on your Mobo to 1:2, with 133 BUS). If running at 133 MHz BUS, PCI divider has to be at 1:4, so your PCI will be at 33,3.

 

[MadTom]

Hmm, try to run the 866 P3 at 100MHz BUS (that is 650 MHz), just to check if it works.