PC Hardware —

Possible Upgrade Scenarios

There are a number of issues to think about when deciding whether to upgrade a CPU or replace a machine altogether. Perhaps the most important issue is the "value" of the upgrade. Will the suggested upgrade meet the operational requirements for that computer? There are limits to what can be upgraded and the results that can be expected from the upgrade. A poor upgrade can lead to total failure and, ultimately, require replacement of the motherboard. Again, the best source of information regarding CPU upgrades is the documentation that comes with the motherboard. The following table lists several possible scenarios for upgrading a CPU.

Existing CPU Recommendation
8086/8088 Cannot be upgraded.
80286 Replace the motherboard with a new 486 or Pentium.
80386SX Same as for 80286. Replace the motherboard.
80386DX CPU has limited use-very slow. Upgrade to a Pentium motherboard.
486SX If it has a good L2 cache (greater than 64 KB) and room to upgrade RAM, and VESA Local Bus consider an AMD486DX/4 or a new Pentium motherboard.
486DX Same as for 486SX.
486DX/2 Pentium upgrade chips will give you some improvement.
486DX/4 Same as for 486DX/2.
Pentium Replace a Pentium 60, 66, or 75 with a faster CPU.

On average, it is more cost effective to replace an entire motherboard than it is to upgrade a CPU. However, you have to judge for yourself. Make sure that the new motherboard will fit into the computer case (check size and alignment of expansion buses) before starting the installation. Be sure that the power supply of the old case and new motherboard are of the same type with the proper connectors (such as AT, ATX). Always make sure that you can return a CPU and motherboard to the vendor if it won't fit. Be sure to determine this before you open the packaging or attempt to install. Keep in mind that many suppliers charge a restocking fee of 15 to 20 percent for returns.