Upgrade the Processor

How to Decide if a CPU Upgrade is Cost Effective

The CPU is often an excellent candidate for a simple, cost-effective upgrade in a one or two year old computer. The prices of CPUs fall like a rock with time, and a top-of-the line $500 CPU will likely be available for less than $200 after a year and less than $100 a year after that. The main physical challenge to upgrade the CPU is usually getting the heatsink off! Some of the spring loaded schemes used to mount active heatsinks require some mechanical sense to remove, so it's not a good upgrade for somebody who tries sticking square pegs in round holes. See my illustrated guide to upgrading a CPU, or the issues involved in a laptop cpu upgrade.

The first issue to look at is socket compatibility. Intel and AMD haven't produced CPUs for the same socket since the late 90's when AMD moved to from Socket 7 to Slot A (Intel had already abandoned Socket 7 for Slot 1). So, before you go shopping for an upgrade processor, you better find your owners manual and find out what CPU the motherboard supports. If you can't find the manual, the motherboard socket normally has the socket type injection molded right on the edge, but it's likely to be covered by the heatsink so you can't read it without starting to take everything apart. Assuming the PC is still alive (if it's not, you're doing a repair, not an upgrade), you can usually find out what CPU you are currently running in the CMOS Setup screens, and along with the processor clock speed, it should be enough to tell you which socket you have.

Now here's the first problem. You can't assume that your motherboard will be capable of running the fastest Pentium 4 or Athlon just because the socket type is correct (keeping in mind there are now three Pentium 4 socket types, the older 423 and the newer 478, and the latest 775 LGA). The CPU and memory speed supported depends on the chipset and the motherboard model. Unless you have the motherboard manual or some experience reading the silk screened settings on the motherboard, you're better off not trying it. If you can figure out the exact motherboard model and version, you can probably get the manual or the information off the web with a quick Google search.

Assuming you find the documentation somewhere and can obtain an inexpensive upgrade CPU that your motherboard supports that's 50% or faster than you're current CPU, you'll likely see enough performance gain to make it worthwhile. Keep in mind that your hard drive will still be running at the same speed, your memory will still be running at the same speed, and their respective capacities will be unchanged. The only thing you're gaining is faster execution of instructions and perhaps a larger on chip cache.

CPU Started in Intermediate Current or planned

Intel Pentium 4 Socket 423 Socket 478 Socket 775

AMD Athlon 64 FX Socket 940 Socket 939

AMD Athlon 64 Socket 754 Socket 939

AMD Sempron Socket A Socket 754 Socket 939 (planned)

Intel Celeron D Socket 478 Socket 478

Intel Pentium 3 Slot 1 Socket 370

AMD Althon XP Socket A Socket A (also known as Socket 462)

AMD Athlon Slot A Socket A

Intel Pentium 2 Slot 1 Socket 370

Intel Celeron Slot 1 Socket 370 Socket 478

Duron Socket A Socket A

Intel Pentium MMX Socket 7 Socket 7

AMD K6 Socket 7 Super 7

So, aside from the technical challenge of choosing a CPU that will work and removing the heatsink without destroying the motherboard, a CPU upgrade can be a real gainer. Don't forget to put some fresh thermal grease on the new CPU, which you should obtain from whoever sells it to you. I wouldn't spend more than $100 on an upgrade CPU under any circumstances, you can probably get into a new motherboard, CPU and RAM for that.

See my illustrated guide to upgrading a CPU or Troubleshooting a CPU