my 600mhz pent iii is recognise as 450mhz on bx6 board

[gorgans]

i have a abit bx6 motherboard. i just upgraded the pentium ii 300mhz processor with a 600mhz pentium iii processor but the computer only sees 450 mhz. i tried changing the speed to 600 in the soft menu in the bios but each time after i reboot it only sees 450 mhz. how can i let it see 600? i also downloaded the latest bios that has support for 600 mhz processor but it still can't see 600 mhz. the specs for the processor is below.





sSpec Number SL3H7
Processor Frequency 600EB MHz
CPUID String 0681
Package Type S.E.C.C.2
Core Voltage 1.65V
Bus Speed 133 MHz
Thermal Design Power 15.8W
Core Stepping cA2
Max Junction Temp 82° C
L2 Cache Size 256K
Die Size 0.18 micron
L2 Cache Speed 600 MHz
ECC/non-ECC ECC
Bus/Core Ratio 4.5
Boxed/OEM Processor? OEM
Product Order Code 80526PZ600256


Notes |

The processor hase an L2 cache with a 64 GB address range, and supports ECC. The L2 cache's ECC cannot be disabled.

More detailed information is available in the Pentium® III processor Spec Update.

[Rainbow]

You must manually configure the FSB speed to 133MHz. The multiplier is locked at 4.5x.

[gorgans]

i tried to manually confiure the FSB speed to 133MHz but when i do that the computer don't boot. i have to clear cmos to get the computer working again. what multiplier and voltage should i use?

[Denniss]

Your CPU needs FSB133 to get full 600MHz due to it's fixed multiplier .
Your mainboard is built of an Intel i440BX chipset officially supporting FSB66 and 100MHz .
Only the very latest ones were able to run with FSB133 .
Stick with 450MHz or use overclocking to get 112MHz - should be reachable with all BX based boards .
OR get a different CPU designed for FSB100 - P3 or Celeron based on Coppermine P3 up to ~1GHz should be OK for your Board .

There's only a very small chance to get your Board to run FSB133 - you need a 1/4 PCI-divisor to run PCI at 33MHz while having your FSB@133 - if this is not selectable from within Bios or with jumper no chance .

[Rainbow]

i440BX chipset works nice even at 133MHz FSB although it's not designed for that. However it has only 1/1 and 2/3 AGP divisors which means that AGP runs at 89MHz (instead of 66MHz) when FSB is set to 133MHz - many graphics cards do not like that. I have Asus P2B (i440BX chipset too) and I'm running Celeron (Tualatin core, modified) 1100 overclocked to 1466MHz (133MHz FSB). My ATI Rage 128 card works at 89MHz but crashes sometimes when heavily loaded (after some time of playing Unreal Tournament of watching DVDs). However some cards don't work at all. If your board does not have 1/4 PCI divisor, it will not work reliably at 133MHz because PCI will run at 44MHz which is too much for many devices (standard is 33MHz).

[edwin]

In short, buy a CPU designed for 100MHz FSB.