1. Check for chipmarks screws. This may give you an idea if it has been unboxed for repairs etc.
2. Hard disk surface scan may reveal hidden bad sectors. As I mentioned in Part 1, as devices get more compact, HDD's are more consealed inside devices and very difficult to replace. As it's a mobile device its always vulnerable to misuse, such as being dropped to the ground, which mainly damages the hard disks.
Usually sellers do not bother replacing the hard disk but try to hide the bad sectors with utilities. No, few bad sectors isn't OK ! Bad sectors is like a disease. Once the HDD starts showing bad sectors it will gradually increase until dataloss is eminent !
Also disk error information can be read from the bios of the hard disk from it's S.M.A.R.T (Self-Monitoring, Analysis and Reporting Technology) database which is embedded into the hdd with a simple free app from internet called Crystal Disk Info.
Also as devices get more compact it becomes harder to service. So if you are going to buy a used device, believe that you are going to be the last user. So it's a Titanic investment.
The best you can do when you buy a 2nd hand/used laptop is that, if it doesn't already consist of a SSD, I strongly advise you to get the existing risky HDD (hard disk) replaced by a new and at least 20x faster and more reliable SSD disk storage.
Unlike HDDs' SSDs' only consist of microchips; so, no moving parts inside, which means less vulnerability to damage. I prefer Kingston SSD drives as they are the most reliable in the market.
3. Keyboard. Though many tend to ignore the keyboard it's the main utility for input. Check the keyboard keys for wears. Every used laptop should have some sort of wear marks on the keyboard. IF it does not, it could mean the keyboard may have been replaced. There are several reasons why a keyboard is replaced including water damage, impact, broken keys.
4. Screen. Check the screen for straches, dead pixels and signs of impact damage.
i. Dead Pixels generally mean, black spots on the screen, due to malfuctioning LCD and no, few dead pixels isn't OK. It affects the view and it can become annoying. Best way to spot dead pixels is to put a total white background image on the screen and look thoroughly for black spots.
ii. General signs of impact on the screen shows itself on white backgrounds at high brightness. Where there has been an impact on the screen, it will show lighter color. The impact on LCD screens are usually happen when the lid is closed and though there may not be any sign of damage on the laptop's cover, the damage on the LCD is permanent.
iii. There can be several other signs of damage on the screen. Anything out of the ordinary is NOT OK, though the seller may try to convince you otherwise.
5. GPU. Although most premium portable computer's (laptops) GPU is embedded into the CPU instructions, GPU is quite important if you plan to play games on the system as 2D and 3D performance may be affected due to defects. Worse, it may cause the system to overhead or defunct in a most weird manner. If the seller allows you, best reliability results can be obtained with a benchmarking software such as 3DMark or BurnInTest.
The most common sort of malfunction on a used laptop is overheating of the CPU and the laptop's power.
on the screen, heating issues (it reveals CPU/GPU malfunctions)
6. CPU. Though the development of laptop CPU's have slowed down, to which generation/version the CPU belongs does matter and can affect the whole system's performance greatly. Though usually, CPUs are quite robust other variables can affect the CPU performance greatly. Looking at Intel's CPU matrix, even the i7 you are intending to buy can be at least 8 years old! So, aim for a machine not older than 3-4 years maximum to have reliable performance and don't waste your time or money for anything that is less than a i5 CPU.
The most important tip regarding the CPU is temperature control. Though CPU's are one robust body, it works with 2 other components: mainboard and the CPU fan.
i. CPU Fan: Most portable computers' CPU fans get clogged with hair, cat/dog hair, dust over time. In the past when the laptop bays were accessible via bay doors, it was a relatively easy task to clean the air ducts but, in today's compact devices, it's nearly impossible. (I know some people put a vacuum cleaner trying to suck out the dust etc, but I do not advise as it can damage the CPU fan). So it is a good idea to check the air ducts for clogging as well as heating on the laptop body (it should not heat so much, even in 3D applications).
ii. CPU Fan insulation/paste: Not just bound for CPUs' of portables but in all devices related to heat, between the CPU and the CPU fan is a substance called "thermal paste" which, generally is a grease with thermal conductiveness, consisting of silver particles. Thermal paste improves the conductivity of heat between the fan and the CPU that enables rapid heat transfer to cool the CPU.
Over time, depending on the usage of the system, the thermal paste tends to get thin, or worse in some cases, melt out. When this happens, the CPU can induct more heat than usual, which may affect the performance of the CPU as the hotter the CPU gets, the slower the CPU becomes. The newer CPU's tend to waste less power and heat up less.
If the casing of the system is hot or above warm, this might be the case and most probably you cannot fix it yourself as the whole case needs to be dismantled. It's a real pain...
5. Battery. Normal laptop battery can go between 2-5 years. For example, I am using a 6-year-old laptop with a battery that still works for at least 1 hour. Badly used laptop's batteries usually malfunction between 1-2 year's time. If the seller is selling the laptop with a dead battery or an unoriginal believe that it may have been misused.
6. Power Adapter. Though many do not take into caution the power adapter, as I mentioned in PART I, power adapters must be preferred to be the original one as most OEM adapters are produced under most inefficient environments and they do lack a lot of the tech that may save your system's life, such as the "grounding" . Also, an unoriginal adapter may be a sign that the system may have been overloaded in its past.
I have witnessed laptops with burnt out mainboards whilst using unbranded/non-original power adapters in even minor power fluctuations.
7. The outer case. Though the seller will do their best to cover the signs of defects on his sale item, you should look for chips, cracks and wear marks under the laptop as well as the corners of the top bezel part as well as under the system. This might sound like a joke to you, but smelling the system can give you a good idea on what may have happened to it in the past such as water damage, overheating (burnt plastic smell) etc.
8. Operating System. It's no doubt that the mainstream operating systems (especially Windows !!!!) are the main reason why the computers are slowing down by the minute. Especially when you start installing software like the antivirus, the system automatically loses performance by at least 35%. Any antivirus/internet security software who says otherwise is just bull%*¤#*ing.
As Microsoft confirms, it's operating systems are unsafe and always vulnerable. Though there are constant updates, it's risky. Though they are vulnerable, after every patch or upgrade it becomes slower. That is how our systems get slower and require more performance every day. That's why the world is full of hardware labelled as "legacy".
Though Microsoft hates it, there are alternatives that bring life back to old/legacy systems called "Linux".
Linux was created by a Finnish university student called Linus Torvalds in 1994. His invention, unlike marketed products, was built on perpetual licensing options, it was built on the GNU Public Licensing model, which allows the product to be used and distributed "freely". Since the first version, the idea took off so powerfully that nowadays it's the biggest competitor of Microsoft.
Bottom line here is, you can bring life into your old system with installing Linux operating system on it, instead of the slow and demanding Windows. There are certain common Linux operating systems (yes, distributions) that has the Windows GUI feel, for a smooth transition, such as Linux Mint Cinnamon. AND unlike Ms stuff, most Linux distributions consist of Office software embedded into them or can be installed free of charge later and is compatible with Ms Office distributions.
OK, I won't boast about Linux further here but also remember that you do not need to use antivirus software in Linux as it's nearly impossible to infect a Linux system.
You can read more about my Linux story HERE.