A few question's that might help with recomending component's to get the best for what he want's and within budget.
What sort of a budget are you looking at max?
What will the pc be used for?
Who will be building it for him?
The Amd quad core's are not bad and neither are the mobo's but personally I would avoid Asrock, and go with Asus or Gigabyte instead.
Ram go for a named brand like the one's you posted because cheap brand's normally are not that good.
Try to spend a little extra on the graphic's card and go for a Nvidia GTX 460 1GB as they are better than the Ati 5770's and also, Nvidia have better driver support than Ati which is a shame because some of there card's are very good but they lack good driver's.
Power supply I would recommend a 600w minimum or a Corsair 750w modular they are more expensive but, it will allow for further upgrade's in the future and also being modular will aid in air flow within the case.
The case is not a bad choice for the price probably the best at that price but having built a pc in it, I know that for a pc such as the spec above what you have posted you will need to add more fans and also mod the, case to fit more in as it is not that good for strong airflow which component's of that nature need.
If you wanted a pc that would last quite a while for a 13 year old then this would be my recommendation:
Case
http://www.scan.co.uk/products/72ant...op-fan-w-o-psu
Cpu
http://www.scan.co.uk/products/amd-p...he-125w-retail
Gpu
http://www.scan.co.uk/products/1gb-g...s-dl-dvi-mhdmi
Hdd
http://www.scan.co.uk/products/ss1tb...-89-ms-ncq-oem
Ram
http://www.scan.co.uk/products/4gb-%...9-9-24-dhx-16v
Mobo
http://www.scan.co.uk/products/asus-...3gb-s-raid-atx
Dvd
http://www.scan.co.uk/products/samsu...sata-black-oem
Psu
http://www.scan.co.uk/products/750w-...-year-warranty
Windows
http://www.scan.co.uk/products/micro...tem-single-oem
Total £730
It is more than the one you posted that he has looked at but this will be allot better and last longer and, not only that but will allow for further upgrades allot easier.
Just a recomendation of course as it is more than you are looking at but it depends really on what it will be used for though in the end.
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7900X3D, 64Gb Corsair 6000Mhz, Gigabyte Aorus RTX 4080 Super, Samsung 980 Pro 2Tb NVME
Unraid Server, 130TB Supermicro CSE-846, AMD Epyc 7551P 32 Core, 64Gb ECC DDR4, nVidia RTX A2000