Every PC has a Central Processing Unit (CPU) this acts as the brain of your system. It connects to the Motherboard and works alongside the other components processing many instructions at the same time between the different hardware and memory systems.
Advancements in CPU technology now mean systems typically come at least Dual Core, Quad Core or more processors (on one single chip) instead of the traditional one core per chip. Now the total number of Cores can slot into a socket as before and a single heat sink and fan can keep everything to the right temperature.
Intel and AMD are the two companies who dominate the PC Processor market. Both have been around for decades and have become the main Chip suppliers for the home and business markets. There are a few other makers but they focus on mobile and tablets and devices like Pi Zero etc use different processors.
Both companies have fierce rivalry and they file and counter file court cases against each other, all we care about is that they have near identical chip products on the market at the same time as they compete for the fastest chip and share of the market.
The competing products are very close to each other and really only the techies compare the benchmarks before choosing. Sometimes Intels latest range is ahead on the benchmarks other times AMD.
Intel Pentium Dual Core Processors
The Intel Pentium processors with Intel dual-core technology deliver great desktop performance, low power enhancements, and multitasking for everyday computing.
Intel i3 Processors (Ivy Bridge)
Intel Core i3 dual core processors provide 4-way multitasking capability, runs at fixed speed ideal for typical tasks and media playback but not games.
Intel i5 Processors
Intel i5 usually quad core but some dual processors deliver the next level of productivity. Mostly the same as i3 but with Intel Turbo Boost Technology, delivers extra speed when you need it. Like the i3 integrated graphics is included but is only ideal for normal use not for gaming.
Intel i7 Processors
Intel i7 processors dual or quad core for the most demanding applications with cache and faster clock speeds. Quad-core processors feature 8-way threading, four cores will run faster, and more L3 cache, but will consume more power. High-end use, video and gaming with dedicated video card.
AMD A4 - These A4 processors have 2 processor cores and include a Radeon graphics chip. Aimed for use with lower end systems.
AMD A6 - A6 processors dual core, includes turbo function similar to Intels allows for the processor to adapt to the task needed. Integrated graphics, on par with Core i3 range.
AMD A8 - 4 processor cores is comparable to the i3 and low i5, its graphic part is faster than Intels version, can handle light gaming with ease.
AMD A10 - 4 processors these quad cores are comparable with the Intel i5, and some i7s should benefit from better battery life.
ASeries processors use the FM2 socket so they will only fit in a Motherboard with FM2.
2013 AMD Piledrivers are the latest version Piledriver then FX-4, FX-6, FX-8 for either 4-8 cores, they use the AM3+ socket so can only be used in Motherboards with AM3+
Each series of processor usually has a couple of generations per series where enhancements and tweaks are made, the main thing to check and consider is that the type of processor is compatible with your motherboard and fits your need and budget.
My personal view is there is little difference between using both makes and have run many stable and fast systems using both makes. The AMD processors do tend to run hotter than the Intel versions, but with a suitable fan this is easily kept under control.
I would decide depending on your budget, don't be afraid of using AMD, the AMD range will mirror closely to Intels in speed and performance and for general use you can use either to run general programs and movie playback with ease. Gaming or video needs you will have a dedicated video card to spread the load and likely a larger budget.
Intel products have in my experience always been consistently more expensive, typically £20 than the AMD equivalent. Throughout my use and builds I find the AMD nearly always more affordable, partly as Intel's products higher price is sometimes because they are available more in retail packaging rather than cheaper OEM offerings, this depends on the supplier.
Don't get to hung-up on reviews, you can view a number of benchmarks comparing the Intel and AMD equivalents head to head, sometimes AMD will be ahead sometimes Intel will be out in front. But unless you are crunching specific tasks you will not notice the odd fraction of a second or couple of seconds here and there.
If you are looking to upgrade just the CPU of your system, then you need to check what type of socket your Motherboard uses and then check what the current speed cpu is against the fastest speed version which can be use in your existing Motherboard.
My advice would be to always look at the whole range of CPUs available as sometimes a small bit extra can get you a significant jump in the speed and performance. Last time I checked a processor with slightly lower clock speed but with two extra cores for just £10 more!
Of course if you are buying a new or barebones systems then you should check both Intel and AMD unless you have a major preference, don’t forget the compatible motherboard and maybe a memory upgrade.
If you can research the type of processor you are buying you may be able to gauge if it is soon to be replaced for a newer series, which could mean the price of your upgrade would be lower as suppliers look to make room for newer stock.
If you are buying an older Processor series you may struggle to find compatible cpus, most suppliers will have a couple of the older type, otherwise you may need to resort to a used, b-grade or auction supplier.