Does the motherboard manufacturer offer a BIOS-update that supports my favorite CPU?
Check the company's homepage or contact your local dealer. Companies usually keep updating their BIOS versions in order to make their products compatible with newer processors. BIOS support is important! Even if your motherboard is able to supply the right core voltage and FSB speed, the system will not run correctly without BIOS-support of the chosen processor.
Which Front Side Bus speeds are supported by my motherboard?
Check your manual for detailed information. Boards with Intel's LX or ZX chipset only support 66 MHz. In that case, you will have to use a Celeron plus a Socket 370 to Slot-1 adapter board. The Celeron requires between 1.5 and 1.65 V core voltage. Please make sure that either the motherboard supports this or the adapter board comes with a fully featured voltage regulator. Any BX motherboard or VIA Apollo Pro supports 66 or 100 MHz (Celeron up to 800 or Pentium III up to 850 MHz). Intel 810E, 815, 820 and VIA Apollo Pro 133(A) support 133 MHz as well (Pentium III 1000 max). Please also check the table above and ask the manufacturer or local dealer.
Let's summarize: The board needs to support the required voltage and Front Side Bus clock. Multipliers cannot be altered, so make sure you get the right processor version (100/133 MHz in the case of the Pentium III). Finally, you need to update your motherboard BIOS in order to support new generations of CPUs. If you cannot get an appropriate BIOS update, then you can only upgrade your CPU by using a faster version of the same processor model that you are currently using. In this case do not switch to another CPU type. Also do not forget to purchase a suitable CPU cooler and fan.
Don't Forget The Graphics Card!
For this topic I would like to refer to one of my recent articles, which deals with the different GeForce 2 graphics chips from nVIDIA. The Scaling Analysis proves that, in case you want to improve your system's 3D-performance, it is usually a better idea to get a mid-class processor plus a fast graphics card instead of upgrading to the fastest processor available. Even a fast Celeron offers good frame rates for nice gaming experiences once it is teamed up with a fast graphics card.