What is a CPU?

Contents

What does a CPU look like
What does the CPU do
How do you measure the speed of a CPU
Types of CPU
Socket Types
CPU Cache
More What Is Articles
Get Prices on the Latest CPU's

This is a beginners guide to CPU's. Please use the articles menu if you require more in depth articles. The CPU is often called the main processor of your PC. CPU stands for Central Processing Unit. When you are buying a PC from a high street store the main selling feature is always the speed of the CPU. You will notice it will say 2.4Ghz or 3Ghz PC. The truth is that the CPU is set at these speeds and has no relevance on what else you could have inside your PC.

What does the CPU look like?

The CPU will likely be the larger of the chips on the mainboard inside your PC. If you have bought the PC from new the CPU will be covered by a heatsink and fan. The heatsink and fan are extremely important. Without these the CPU would get too hot to work and possibly melt or burn out. Be very careful to replace the fan correctly if you remove it to have a look at your CPU.

What does the CPU do?

The CPU is the main processor of your PC. Everything that goes on in your PC at some point goes through your CPU. In reference to the human body the CPU is brain of the PC. It is artificial thinking but the CPU is where all the logic is applied. As a very basic example computer code is basically mathematics. if you wanted to calculate 2+7 you would need an input an output and a processor to add the logic. The logic in this case is simple addition. You would input 2+7 on a keyboard. This would be registered and sent to the CPU for analysis. The CPU would see that the addition logic is required and use this inbuilt logic to send the answer of 9. That of course is a simple instruction but the idea for all processors is the same. Input > Apply Logic > Output.

How do you measure the speed of a CPU?

The CPU's speed is a measure of MHz (megahertz) or more recently GHz (gigahertz). a chip with a megahertz rating of 900Mhz would be able to complete 900Million cycles every second. However don't be fully deceived by this figure alone. This figure only shows how many clock cycles the CPU can do in a second. How much being done in each cycle is another matter. I urge you to check out some benchmarks on CPU's before you you decide that the one with a faster rating has the best performance. Unfortunately the need for speed and higher clock rating have driven the CPU industry to work on this factor without really seeing what the performance of these chips are like.

Since CPU's have started to top out at fast speeds now, the major manufacturers are looking for ways to increase the processing power without increasing the actual speed of the CPU. The route they have taken with this problem is with multi-core CPU's. On a single chip these new processors have 2, 3, 4, or even more processing cores fitting. These cores chare the workload and process faster than traditional CPU's even though they are not rated at higher speeds. So remember don't just look at the rated speed as now more than ever this doesn't give you the full story.

Types of CPU

There are two main desktop CPU manufacturers, they are Intel and AMD. Both of these companies have a power CPU and a Budget CPU. The Power CPU's are the Core 2 Quad from Intel and the Phenom X3 and Phenom Quad from AMD. The budget CPU's are the Celeron from Intel and the Sempron from AMD. Price is a big factor between these CPU's. Check the latest prices of these CPU's below.

AMD X2 (Dual core CPU)
AMD Phenom X3
AMD Phenom Quad
AMD Sempron
Intel Core 2 Duo
Intel Core 2 Quad
Intel Celeron

Socket Types

Each range of CPU fits into a specific socket on your motherboard. motherboards are design with one socket type and cannot be made to take another. Socket types changes quite rapidly, a socket change usually happens when a new breed of CPU surfaces. A new CPU with a new layout requires to connect to the motherboard differently and so a new socket type is released on motherboards to handle the new CPU's correctly. Even if a CPU fits into a motherboards CPU socket Physically, there is no guarantee this will work. Always check the motherboards documentation for supported CPU's before making a purchase.

Socket Type	Compatible Processors
Socket 7	*Original Pentiums, Cyrix 686, Cyrix MII, K6, K6-2 and K6-III*
Socket 370	*Intel Celeron, Intel PIII (not Cartridge), Cyrix III*
Slot 1	*Intel PII, Intel PIII (cartridge only)*
Slot A	*AMD Athlon (Cartridge only)*
Socket A	*AMD Athlon Thunderbird (not Cartridge), AMD Duron, AMD Athlon XP*
Socket 423	*Intel P4*
Socket 478	*Intel P4 (2nd Gen)*
754-Pin Socket	*Athlon 64*
940-Pin Socket	*Athlon 64-fx, Opteron*
Socket AM2	*Athlon 64 FX, Athlon X2*
Socket 603 / 604	*Intel Xeon*
Socket T	*Intel Pentium 4, Pentium Extreme, Pentium D, Core 2 Duo*
LGA 771	*Xeon*
PAC418 / 611	*Intel Itanium*
Socket 775	*Core 2 duo, Core 2 Extreme, Core 2 Quad*
Socket AM2+	*Athlon 64, Athlon 64 FX-62, Athlon 64 X2, Sempron, Sempron LE*
Socket AM3	*Athlon 64 X2, Phenom, Sempron, Sempron LE, Opteron*
Socket F	*Phenom, Opteron (Server range)*

The CPU's Cache

The Cache on the CPU is a small amount of very fast memory which is situated on the CPU. the cache memory is very expensive which is why its available in very limited amounts. The CPU cache acts as the repeated memory storage for data that the CPU requires frequently. Having more on-die cache speeds up processing as the CPU doesn't have to wait to retrieve data from the main memory, which in computing terms is very slow compared to the cache. It ranges from about 64Kb to 4Mb and soon larger cache chips will be coming. For more information on CPU cache and how it works we have just the article. How does CPU cache work.

More articles in the What is Category

What is your Motherboard
What is your Graphics card
What is your RAM
What is your Hard Disk

Still unsure? please ask at the PantherProducts Forums where we may be able to help you out