If you need 32GB of ram then go with the HP 8300 instead of the 8200. You can use ram from other companies in the MT 8300. Even the brands like G.Skill Ripjaws that has tall heat spreaders. Brands like Corsair or G.Skill don't seem to work well in the 8200 as HP had more restrictions on which ram was supported. Here is the best 32GB ram kit to use in the HP 6300 Pro MT or in the HP 8300 Elite MT. The DVD drive restricts their use in the SFF model, clearance issues for the heatsinks.
https://www.newegg.com/Product/Prod..._re=G.Skill_ripjaws_10-_-20-231-569-_-Product
You could also buy two 16GB kits and save a few dollars. The ram will only run in dual channel mode not quad channel anyway.
https://www.newegg.com/Product/Prod..._re=G.Skill_ripjaws_10-_-20-231-568-_-Product
Also, the i7-3770 is the best choice if you want an i7. It gives you compatible HD4000 graphics which are nice to have for various reasons. The 8300 also gives you 4 onboard USB 3.0 ports. The 8200 only has USB 2.0 onboard. The HP 8300 i7-3770 version will cost more but you will get a much longer useful life out of it than the HP 8200 with the i7-2600 CPU.
Read all about this in the Sierra version of the 8300 guide.
https://www.tonymacx86.com/threads/...orking-and-easily-affordable-customac.224812/
What websites will you be ordering from ?