Jumper setting.....

[Libcomer]

Putting together a new mobo with a AMD 850MHz athlon processor and the one jumper is Cpu System Bus Selector that states (use this 3-pin jumper if the processor runs on 133MHz or 100MHz system bus. Does anyone know which bus speed this runs at? Would the system bootup if I had it the other way?

[ranchdog]

Welcome Libcomer.... The 850 Athlon uses the 100Mhz jumper setting. As it is a B series.
AMD processors 1Gig and above can use 133Mhz or 100Mhz depending upon whether the CPU is a B or C series chip.

B Series use a Front Side Bus of 100Mhz and it is doubled to 200Mhz when it reaches the CPU.

C Series us a Front Side Bus of 133Mhz and it is doubled to 266Mhz when it reaches the CPU.

If you look at an AMD CPU chip-die closely, there are three rows of numbers and letters. The last letter on the TOP row will designate either B or C.

Some Motherboards will only support the B Series CPU. Some will support both the B and C Series CPU. As does yours.

As to your question will your 850 boot up if jumpered the other way. By default, it's not supposed to. A C Series chip will boot if configured as a B model but will be underclocked.

Luck.

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......Indecision may or may not be my problem......
...... Kickin' A Rock....

[This message has been edited by ranchdog (edited 09-28-2001).]

[Libcomer]

Thanks ranchdog.

I had this same computer working once and I had a 128 ddr ram installed. I then took out the 128 ddr and replaced it with 256 ddr board and when I turned it on, all I get is 3 short beeps from the bios and no video. I asked the person who I bought the 256 from and he stated that he tested the 256 ram before he sold it to me and that it isn't the ram that is bad.I was looking at other things that might be causing the problem but it seems to me that the problem probably is the memory.
Thanks again,
Libcomer

[vantim]

Yes he's correct the duron uses a 100 mhz bus check here for details: http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_608,00.html

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Tim Jones MCSE