What should be considered when buying or assembling a new computer? How to tell if a computer is powerful or not?

There are 4 main factors that make a computer "good", ordered by importance level below.

1. Hard disk
2. RAM
3. Graphics card
4. Processor

Hard Disk : The storage device where the programs will be installed and the data to be read when they will run. While only HDDs (Hard Disk Drives) were used as hard disks in almost every computer until 10-15 years ago, SSDs are more preferred today due to the development of high performance SSD (Solid State Disk) technology and the decrease in prices. The classic hard disk type HDDs are mechanical disks and consist of disk plates rotating 5500 or 7500 rounds per minute as standard and a read-write head that reads the data on them. On the other hand, SSDs are the disks that do not have any mechanical parts, consist entirely of electronic (flash) memory and read-write the data electronically at high speeds. SSDs are about 7 times faster than HDDs, but their price increases as their capacity increases.

Since the hard drives are the main center of data flow, which is the most basic operation in computers, they affect the system performance in the first degree. Therefore, a good computer must have at least one SSD. SSDs can be used with HDDs, which is the most common use today. In typical usage, data such as video, music, documents or photos that not being read-write frequently are installed on the HDDs while the operating system and frequently used programs like games are installed on the SSDs. In summary, the first thing to be aware of when buying or assembling a new computer is that the computer must have at least one SSD drive. The minimum amounts I would recommend are 256GB for SSDs and 500GB for HDDs.

RAM (Random Access Memory) : When a program or game is to be run on the computer, the data of the relevant application is always copied from the hard disk to the system memory called RAM and the process is done through it. RAMs are consist of electronic memories like SSDs, but they do not store data permenantly but temporay: This means, when the program or computer is shut down, the data on the RAM deleted. In addition, RAMs run much faster than SSDs.

During the running of games or programs, if the capacity of the RAM runs out and there is no free space while the data is transferring to the RAM, the new data is written to the file called "pagefile" which been used as Virtual RAM by operating system on the hard disk and the operations continue to be done through this file. At this point, if your hard disk is an HDD rather than an SSD, a serious slowdown in operations might be encountered. Even though SSDs are relatively faster than HDDs, there will still be some performance loss as they cannot beat the performance of RAM. This is why the amount of RAM in a computer is very important. A good computer today should have at least 6GB of RAM. Of course, if you have enough budget, it is much better to increase it up to 16 or even 32GB.

In addition to the capacities of RAMs, the operation speed (clock frequency) also affects the performance, but this will not make a serious difference, and most of the RAMs today are already fast enough.

Graphics Card (VGA) : The Video Graphic Adapters (can be called also video card and graphics card) are responsible from graphic operations and they are the key factor of entire graphics peformance of computers. They come ready as embedded in all laptop and desktop computers' motherboards, so you do not need to purchase a separate video card for your computer to run, unless you play games or use graphic-video design and editing programs that require high graphic processing power. In order for such applications to run at high performance, they need powerful GPUs (Graphic Processing Unit) and high capacity of VRAMs (Video RAM). Otherwise they will not even run.

That is why external video cards are produced and used. External graphics cards come in their own slots (PCI-Express) in addition to the embedded graphics card on the motherboard in laptops. Of course, not every laptop has an external graphics card. Especially inexpensive systems only have an embedded standard graphics card, which is generally low in performance.

A good video card can be recognized from the high clock frequency of the graphic processor, the bus bandwidth and the high capacity of the video ram. You can see these details when you buy a video card, but when you buy a new computer (especially laptop), you can only see the model of the video card and the video ram usually. Whether you are buying a video card or a laptop, you can find out how good the video card is from the site called videocardbenchmark.net, which I also benefit from and experienced its accuracy.

There are two brands that dominate the graphics card market today; Nvidia and AMD. Both of them have very high quality and powerful graphics cards, so if you are looking for a good graphics card, you should get one of these two brands. However, I recommend that you research the model of the relevant brand you have chosen or seen from the site I have given. Apart from these two brands, graphics cards of Intel which is one of the two giants (with AMD) of the CPU (Central Processing Unit) market, continue to be developed day by day, but they are still mostly in the market as an embedded standard graphics card.

If I need to give advice on the graphics card based on a model; I'd recommend at least Nvidia's GeForce GTX 1060 or AMD's Radeon R9 Fury.

Processor : Processors, namely CPUs (Central Processing Unit), which are the brains of the computers are the hardwares consisting of millions of micro transistors that undertake critical tasks such as energy, memory management and the data flow in computers. Although the processor performance is most prominent in video-graphic processes (rendering) and games, since the processor technology is very advanced today, most of the processors in the market can deliver the desired performance. For this reason, although there is no need to think too much about the processor, I can recommend at least one of Intel's i7 processor family, one of the two leaders of the market, or a model from the Ryzen series of AMD, the other giant. You can also use the cpubenchmark.net website, which is the processors version of the site I recommended for the graphics card above for comparison and detailed information.

In addition to the issues I mentioned, warranty and service opportunities are also important, especially for laptops. The most successful brands in this regard can be listed as Monster, Lenovo, MSI and Asus. It is useful to pay attention to this issue when purchasing a new computer.