For serious gaming, you have to go to a serious gamer's shop in deep Akiba...
〒101-0021 東京都千代田区外神田 3-16-18 通運会館 1F
Plug that address into google maps. You can also see their website here...
https://www.ark-pc.co.jp/info/shopguide.html
Also, near Ark is DOSpara.
〒101-0021 東京都千代田区外神田3-11-2ロック2ビル1,2F
http://shop.dospara.co.jp/pc/shop/information.htm?dir=hon
And near that is Buymore
〒101-0021 東京都千代田区外神田 3-14-10 秋葉原HFビル1F
http://www.unitcom.co.jp/buymore/
And right across the street from Buymore is Sofmap's large PC DIY shop.
And best of all, there is a kebab place located in the center of all of those points! If you can't find what you are looking for in those 4 shops, it just isn't to be had in Akihabara, period. Ive bought everything portal plush cubes to a US-spec Battlefield 4 Razor keyboard to an exact model of bulk hard drive from one of those many places.