There are a couple of things that you must do before and while upgrading your machine or its components. This might take a little while, but will definitely save you from getting in big troubles.
Backup your data
First thing you should do before upgrading your system is performing a full backup of your data. It is very necessary, as you never know what things could possibly go wrong during the upgradation process. No matter how hectic it may seem, but this little effort can really save you from getting in some big time trouble.
Clean the interior of the CPU
A lot of dust bunnies settle on many delicate components of CPU over a sand of time. If you don’t often open your CPU there is a good chance that you will see a lot of wires untied, loose and messing over each other, it is very important to clean the mess and make it ship-shape. You can clean the well settled dirt by using your old toothbrush, and after that, use a vacuum cleaner to suck up all the dust.
If your computer is old enough, your motherboard is likely to have AGCI, Adaptive Host Control Interface, disabled. AHCI makes your motherboard compatible for booting off a device larger than 2.2 TB. It also enables several other functionality, including, hot swapping and command queuing.
Make sure to turn this feature on, if you’re going to format your system and setup a new hard drive or SSD. But do not alter the settings if you’re not going to do a clean install, because then your Windows 7 won’t even boot.
Gear up machine’s cooling system
If you are going to setup a new processor, or a graphics card or if you are thinking to overclock it to some higher value, you should consider upgrading your heatsink fan. With the upgradation of your processor or any other CPU component; your computer not only becomes fast, but it also radiates more heat. Installing an additional fan, or changing the existing one (or cleaning it properly and removing out all the dirt) will let more air pass over the components and will keep it cool.
Check the PSU (Power Supplying Unit)
You just upgraded your GPU card and all of sudden the PSU started acting weird? Well, it will get only weirder after a few days. Before setting up a new motherboard, GPU or just a processor, see its manual or contact the vendor to double check its power needs and make sure your current PSU can handle it.
Never reuse your thermal paste
Just upgraded your CPU or heatsink, and going to reapply the old thermal paste? Not so cool buddy! (literally)
It is highly recommended that you wipe off the older paste and reapply a new layer of paste.
Speaking of applying thermal paste, very often people ask me how much paste is required. Well, the answer is you have got to be sure that it isn’t just too much, and neither too less, it should be medium layered, covering the entire surface. If the old thermal paste has glued on the surface like concrete, you may require putting some organic solutions like Arctic Silver’s ArctiClean, or about 95 percent isopropyl alcohol.
Don’t throw the old parts
So you installed another optical drive to your computer and upgraded the GPU. What are you going to do with the older slot cover, and other spare old components? Throw them away?
Well, don’t do that. In future when you will need to put that cover back or for some reason need it, this piece of junk will come to service again.
Check the airflow
Since you have tinkered with a few components, you might have displaced many a drives in that process. Or, the new component, its position, the way you have tied the wires might prevent the air to flow from end to end inside the CPU. So it is very necessary to check if they are working properly and if not, you should reposition and adjust the fans, if required configure the fan speed.
Perform a clean reinstallation of OS
Despite how hectic it may sound, but re installing the Operating System after you have upgraded your graphics cards, swapped the motherboard and chipset it is highly recommended that you re-install the OS. There are good chances that recent changes you just made to your computer might face compatibility issues with your previously installed OS.