Lucifer02

Based on Crucial's RAM configurator, no - they only provide SSD upgrade instructions because the RAM is soldered to the motherboard.
https://www.crucial.com/usa/en/compatible-upgrade-for/Lenovo/ideapad-720s-13ikb

The RAM is soldered, so no
 
x4 PCIe lanes TB3

I love my QC35s. besides sound quality, and noise-cancelling, i never realized how liberating it was to stand up and walk around without taking my headphones off

In my opinion you should go for the bose headphones, they are super confortable and their sound isolation is amazing. If not then go for the sennheiser.

I would say go Bose, they've got one of the best all rounder headsets out there. I've been using the original QC35s for years now and I still love them. Linus posted a video about 3 of the 4 of those headphones (the 4th of which was garbage beats), comparing them here if you want to check it out. And it also seems he posted a different video between the Bose and Sennheisers as well here. Hopefully this will make your decision a little easier.

USB C doesn't mean that it has Thunderbolt which is used for eGPU
 
Any preference on weight and battery life? Mind low sRGB display and non-upgradable RAM?

maximum kg/lbs you can accept?
fine with non-upgradable too?

hey, if you don’t mind using Used Product then you can check this out. You will need an eGPU if you want to game in it.
 
https://www.ebay.com/itm/Razer-Blade-Stealth-13-3-QHD-Touch-Screen-Laptop-Core-i7-16GB-Memory-512GB/202621161412?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D56829%26meid%3D8d6e66fc2cf54ee0a122ae59303475a2%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D202621161412%26itm%3D202621161412&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Ac3bdb2f8-4609-11e9-a94a-74dbd180b427|parentrq%3A7a41f38b1690aa48ecf5ef13fff6717a|iid%3A1

Dell XPS 15 9570 iGPU - upgradable RAM
HP Spectre x360 13-ap0008ca
Lenovo Yoga 730 13 81CT001TUS / customize (16GB)
Lenovo Ideapad 730s 13 81JB0007US / 81JB0008US - no USB A
Lenovo Ideapad 720s 13 81BV002EUS with UHD panel

Your budget is a bit tight for a TB3 laptop
 
Dell G5/G7 (i5-8300H+1050), has low sRGB IPS though. Battery life can stretch to 6 hrs
 
If you prefer Ultrabook, Ideapad 720s 13. Note that laptop with KBL-R/CFL-U CPU and dGPU will NOT have x4 PCIe lanes TB3 due to chipset limitation

use ddu for uninstalling your display drivers as elpiop said

did you uninstall your old gpu drivers and reinstall the ones for your new card?

It will be fine if the fan is facing down.

That's fine, it's more of a personal preference if you want the PSU to exhaust case air or not, In your case *pun intended* you have no top PSU grill, so the PSU really has to exhaust internal air, this is ok, most cases don't even have that hot of an internal environment anyways. I have a very nice Corsair RM850x, it's a nice PSU, good quality. I have it facing fan side up, as it's fan never come, which is ok if you don't mind it running about 40-50°C, however I know that electrolytic capacitors loose life exponentially every 10°C hotter they run, so by forcing some case air into it and cooling it passively, the PSU can run cooler, and thus increase capacitor life by about 3 orders of magnitude over normal, something else in this PSU will fail before those capacitors hopefully, unless there is an outlier for quality control. 

The fan goes wherever it gets the freshest supply of air, in your case only one option.

I had a case like that when the PSU fan first became a thing... worked fine for years, even 24/7 operation. You'll be fine

guys who all agree that this is by far the best air cooling method available till date?

This is not your Windows key. Your Windows key is under your system on the label

guys who all agree that this is by far the best air cooling method available till date?

no problem. Glad I can help!
 
For the Phone activation:
When and if the activation fails, you'll have a message box appear. You'll have the option to do a Phone activation (your other options is to enter a new key or buy Windows). Click on Phone Activation. Clicking on that option will ask your country/region, enter it, and you'll see something like this:

 
You'll see the phone number the dial for your region (the picture above is a random one from the web). Pick up the phone, and call the number. A machine will pick up, ask you what product you want to activate (going by memory, for my region, may be different for you), so it will say something like: Office, Windows, etc.. and you say Windows, and then it tell you to say the numbers that you see on the screen on the above picture. So it will tell you to say the number in Group 1. And if we use the picture above as an example, you'll say or dial in: 013272, and it will tell you to say or dial group 2, and you say or dial: 525215, and so on. Then it will activate, and give you a set of numbers that you enter in group A, B, C, D, E, F, G and H. If activation fails, it will transfer you to someone, who will ask you questions like, how many Windows you are using with the same product, which you say 1, as that is your case, and then might ask you what you are trying to do, and you say, you changed your HDD to a SSD on my system, and re-installing Windows, and then he or she will give you the numbers to enter in group A, B, C,... and so on. Once done click on Next, fi no error was typed i, it will activate.
 
 

Get Windows edition ISO file (so if you have Windows 7 Home Premium, get Windows 7 Home Premium 64-bit OEM), and burn it to disk or extract it to a USB flash drive. Use this tool for Windows Vista, 7, and 8: https://rufus.akeo.ie/ (Microsoft had an easier tool that you can use, but it doesn't exits anymore due to its age, and Windows 10). If you don't have the ISO file, then ask a friend for his/her disk of the right edition and use that instead. Remove your HDD Plug-in your SSD to your system. Tell your system to boot from disk or USB flash drive that contains Windows Install Windows Enter the product key that is under your system Activation may fail, if so, do a phone activation. Install all missing drivers Do Windows Update, once done, do it again, and again and again until no more updates shows. Plug your HDD to the system in addition to the SSD if you can, and copy your files from the HDD to the SSD.  OR plug it to another system, network share the drive and copy your files over, OR get a USB adapter (powered is needed for desktop HDDs), and plug the HDD to it, and plug it to your system, and transfer your files. If you have none of that. Plug back your HDD in your system, don't connect on the web, get blank DVD's and backup your data to it / them. Once done, remove the HDD, plug back the SSD, and copy the data from the DVDs back to your SSD

For Windows 8 and 10 (and late Windows 7 systems when EFI reached the PC market), manufactures have a process in storing a unique product key in their UEFI chip. That is why you don't have those Windows product key stickers anymore. You install the OS, Windows will see the unique product key stored in the UEFI, and do the activation process. In other words, it is like you bought Windows at the store, and the key was entered for you.
 
For Windows 7 on non-EFI system and prior, it is a bit complicated (BIOS were used in systems at the time). The install media is made by Microsoft (and can be reproduced by the OEM to include in the box, but as most people threw their box and all disk soon after they get their computer, and to be price competitive and maximize every penny for profits, OEM stop including it, and gave you this crap image utility system. Fun fact.) The manufacture DO USE a generic key, but not manually entered, it is stored in some file on the disk which tells Windows Activation system to look for the unique product key on the BIOS chip, and assume it is activated. So, if you called to order your system, and you request the installation media (usually it was free), and you decide to clean install Windows with the disk provided specifically, then you would notice that no product key was ever asked, and Windows is activated even before you connect yourself to the internet. If you check using standard tools for the product key, it will be a generic key... if you use it on another system, say one that you built, or a pre-built system from a different brand, it will not work. Windows will go in trial mode. Dell had its key, HP had its key, and so on and so forth. The problem with this method, is that the key could be easily extracted from the BIOS, and stored on another system, and using the same disk (or a copy of it), one can illegally pirate Windows, and never have to worry about activation problem, ever. This was a serious problem for Microsoft, as you had many smaller manufactures around the world that made tools to code their BIOS to have the key and have a disk image of a manufacture, and allow to have Windows treat their system as if it was made by Dell, HP, etc.. have Windows activated, no piracy tool needed, no system file modifications, and can't be disabled by Microsoft as the OS would not even do the online activation. Note: Apologies for some inaccuracies and missing details, it's been a long time.

it was the pre-installed version nobody ever bothered to change it in the last 5 years and now I'm finally taking up the job

you have OEM win 7 so you should have a sticker on the case with the product key on it

That is not the key,it is the activation id,download a tool like Produkey and use that to get your key and use that key to install Windows.