You mean https://www.overtek.co.uk/
? The ship from UK and UK is not in EU - it means that I have to pay VAT + duty, it means +28%
If there is a reseller in EU, I'm really interested then.
1. No duty. There are no import duties on computer parts providing the seller allocates the correct tariff / HS code ie 8504403000 or 85044030 for a computer psu. This has been the case since 1997. One current exception, goods from Russia or Belarus are subject to 35% duty in many countries
2. If seller a is IOSS, like overtek, you will pay VAT up front at your country rate if the amount is 150euro or less. If above that amount then you will pay no vat up front and it will be handled by the delivery service/courier. They will charge you a vat deferment fee along with vat due.
If a seller outside EU is not IOSS you will pay VAT and deferement fee for any amount.
If customs judge a declared value to low they can decide to asses its value, unless you can prove otherwise.
So in short IOSS avoids the deferment fee, varies by country usually around 12 euros, for orders under 150euro
The EU moved in July 2021 iirc to collect vat regardless of value. So all big ecommerce selling into EU have to do IOSS, including aliexpress. This was to A collect more VAT and B have a more level playing for business in the EU as they have to charge VAT. hence the no duty no vat for 22euro or less was dropped.