Since the 486, processor upgrades have been relatively easy for most systems. With the 486 and later processors, Intel designed in the capability to upgrade by designing standard sockets that would take a variety of processors. This trend has continued to the present, with most motherboards being designed to handle a range of processors in the same family.
To maximize your motherboard, you can almost always upgrade to the fastest processor your particular board will support. Because of the varieties of processor sockets and slots—not to mention voltages, speeds, and other potential areas of incompatibility—you should consult with your motherboard manufacturer to see whether a higher-speed processor will work in your board. Usually, that can be determined by the type of socket or slot on the motherboard, but other things such as the voltage regulator and BIOS can be deciding factors as well.
For example, if your motherboard supports Socket AM2+, you might be able to upgrade from a dual-core Athlon X2 or quad-core processor in the Phenom II family, because they all can use the same socket. Before purchasing a new CPU, you should verify that the motherboard has proper bus speed, voltage settings, and ROM BIOS support for the new chip. Visit the motherboard or system manufacturer’s website to obtain the most up-to-date processor compatibility information and to download BIOS updates that might be necessary.
If you are trying to upgrade the processor in a preassembled or retail store-bought system, you might have few processor upgrade options using the BIOS provided by the system vendor. If you can figure out who made the motherboard (and if it is not a proprietary unit), you might be able to contact the motherboard manufacturer for a more updated BIOS that supports more processors. You can also use the BIOSAgentPlus website (http://biosagentplus.com) to scan your computer, determine if a BIOS update is available, and download it.
Upgrading the processor can, in some cases, double the performance of a system. However, if you already have the fastest processor that will fit a particular socket, you need to consider other alternatives. In that case, you really should look into a complete motherboard change, which would let you upgrade to one of the latest processors at the same time. If your chassis design is not proprietary and your system uses an industry-standard ATX motherboard design, I normally recommend changing the motherboard and processor together rather than trying to find an upgrade processor that will work with your existing board. Keep in mind that new memory might also be necessary.