If you have trouble with your PC running slower, and you've already done all the recommended clean your hard drive advice, and you just need to churn out more from that PC engine. Normally its only really gamers that require this but also more so desktop publishers, and high performance software users. Upgrading your CPU, can be the difference between having 2 or 3 programs open at the same time, and switching between them with a slight delay, and being able to do the same except having no delay between the switching.
Upgrading your CPU will allow your pc to handle more instructions per second, and certainly with some of the software being made these days, as well as web applications every little extra push helps.
The first thing you will have to decide on in upgrading your CPU is if its actually possible. The thing that decides this is the motherboard. If you have an older pc, you won't be able to run down your local pc store, buy the newest cpu and plug it in. That is just like plugging a Lamborghini engine inside your Volvo. You might be able to plug a ford or a a vauxhall into your volvo, but that would be about it. As technology moves on so does the motherboard and cpu technology. The easiest way to think of it is that each motherboard step in technology can handle about 3 to 4 improved CPU designs, before the next CPU design will no longer work with that motherboard and a new one is required, starting the whole cycle again.
However, don't let this stop you. If you find out what type of processor you have and your motherboard, you should be able to get a CPU upgrade. Even if you have to buy the CPU from ebay second hand then you will still be able to squeeze a bit extra out of that ancient pc you have.
You will need to consult your motherboard guide as to what type of CPU speed they can handle going up to. Normally its easy to figure it out, as the CPU manufacturer make a great effort to brand their new CPU technology. An example is that if you have a pentium 4 CPU, there is a number of different clock speeds that the cpu will run at. Your motherboard manual will tell you how high the clock speed will work with the motherboard. The CPU's that are made now are called quad core CPU's, and this is far different from pentium 4's. The concept remains the same though. There are a variety of quad core cpu's that increase in speed and price. No different from the older pentium 4, or even the very first Pentium. There is always an incremental increase, and then a specific limit.
Once you've figured out your motherboard, and the CPU that you have, then you will want to buy your new CPU. Once you have it installed you can even sell your older cpu and get some of your money back.
Fitting the CPU
To fit a CPU, make sure your pc is switched off first. You will then need to open up your pc case, and get access to the motherboard. You will find the CPU as the largest part with a fan attached to it. You will need to unplug some of the power cables from the hard drive,and anything else that gets in your way to get your hands into the cpu area. There will be two metal type or plastic type clips that attach this huge chunk to the motherboard. You will need to use a small screw driver to very carefully push the clips out, and release the cpu. Once you've done this, you will be able to remove the fan with the attached heatsink. This will leave the CPU exposed in its little housing, which will have a small lever to the side. its this lever that locks the cpu in place, so you will have to release it carefully. This will push back the cpu slightly, and allow you to pick it out. You will have to do this very carefully as a cpu is made up from many pins, and they can easily be damaged if your not careful.
Take the cpu out, and then place it carefully somewhere safe. Then take the new cpu and lot it into the same location as the cpu was. You can only place it in one way, which is normally shown with a little triangle, or a rounded cover, and matching symbol on the plastic housing. The cpu should drop right in, easily. You should never have to push it in or use any force at all. It really should be so easy, and a perfect fit. If it isn't then check you have it the right way around, and rotate 90 degrees until it does fit. If that doesn't work then you have defiantly bough the wrong cpu. I will assume though that you didn't.
Now that the cpu is in place you will need to close the lever again, which will feel a tiny bit rigid, as you push it back down, but don't worry you won't break anything as long as your careful. The fact that the cpu has slotted in means that the most dangerous bit is completed. Once the lever is down, you can now replace the fan, which you took off before. A good tip also is to get some cooling solution that sits on your cpu, and conducts the heat to the heatsink. you only need a little, and its very cheap but makes a great difference.
Once you've got your CPU in place, and your fan is located on top, then you can push the little levers over the locks again. This can be one of the most tricky things to do on a pc, depending on the type of motherboard, however recently manufacturers have made it easier.
After you've got everything in place, just reattach all your cables,and secure your case, and power it up, and your off, brrrmmm brrrmmm