PC Build for Ecommerce+video editing

E-Commerce is a broad category. I've dealt with people who do stock trading, run an online businesse, online accounting and other remote work. CPU and GPU wise they usually don't need anything special. If their video editing is just something simple like personal videos. When it comes to custom built. I believe in only using high quality parts. If they want cheap. They can buy a Dell and you can slap a large SSD and more RAM in it. If all they care about is price. I’d just do a Dell, ASUS or Lenovo which includes the GPU. Then upgrade the RAM and SSD yourself. You aren’t likely to beat the price.

CPU: Either is likely more than enough.

GPU: Don’t know how much they care about gaming. It’s probably fine.

RAM: I’d only use Crucial or Corsair. If they are very active on the computer with numerous open tabs, multiple business programs running, VMs. They can use a lot of RAM. I don't know their uses. I have one who fully uses 24GB right now. They are ordering a new computer. So, I recommended 64GB. As 32GB won't last long at the rate they are increasing usage. I couldn't say what would be enough for Your client. I don't know their usage. Most are fine with 16GB. I look at their usage in binary intervals. 4GB, 8GB, 16GB, &c. If their current usage is more than half of a given tier. I recommend the next tier up. Say they use 9GB. That is over half of 16GB. Their new computer should be 32GB. So, that they most likely won’t have to worry for the next four or five years.

SSD: If the person is wealthier and wants a lot of speed. I'd suggest a larger SSD. If they are interested in video editing. I'm assuming they also have a lot of family photos. I'd do 1TB on the SSD. As you are building it for them. I'd only use Samsung. They won't care about £20 when it comes to reliability. NVMe if budget allows.

HDD: Hitachi (HGST), Toshiba, Western Digital. Someone anyone. Just not Seagate. They have a horrible record.

Backup: What are they going to do?

Input: They are going to use that keyboard and mouse all day. Get the Logitech MK700 set instead. It’s a very nice keyboard and mouse combo. I’m not aware of any wireless mechanical keyboard.

Motherboard: They want a custom computer. They want high quality. They don’t know what they need. You tell them why they need a good one. Use a high-quality unit. Not some bargain basement ASRock. ASUS Strix B350-f for the AMD and ASUS ROG Strix Z370-H or ASUS Prime at least ASUS TUF Z370 Pro Gaming.

PSU: I’d give them a little breathing room. You don’t want to come back in two years and say. You need a new PSU for that upgrade. Because I was trying to save you £15.

WiFi: The detached antenna is great. Since you want the antenna away from the case. I’d go with something at least AC1200 and dual or even triple antenna. Just keep the antenna detached like the Gigabyte.

Case: It’s probably fine. I’d go with something from a more premium brand. Such as Corsair, NZXT or Phanteks. The S340 and P400 are good units.

CPU Cooler: The Cryorig H7 is fine.

OS: Good you went with Pro and the full retail. So, they can transfer the license. Don’t forget to register it with their Microsoft account.

Monitors: I couldn’t say. The bigger the better. If they have poor eyesight.

Let them buy the parts. They pay you for the labor. Then you aren’t on the hook for a warrantee of the system. Which seems to be heavy in the UK. It also just makes warrantees less of a hassle. Charge them a consultation fee for selecting the parts for them. That way if they decide to do the work themselves. You still get paid for your time. Labor is much more profitable than markups on parts.