Looking at the internals you got one of those units that sell under many different names and is frequently used in fake/lower quality flex PSUs.
For example here they sold it as DELTA 500W PSU:
Hi, I just had an Ebay purchased Delta DPS-500AB-5B 500W platinum rated power supply fail pretty spectacularly. Upon opening it up, I discovered that the general build quality and general layout/materials did not match up with the previous Delta 400W gold rated unit I had used in a previous...
smallformfactor.net
You can compare your pictures with the teardown I did on the MF-700F
Update: OVERTEK now offers the original ENHANCE 7660B pre-modded with a Noctua fan for a reasonable price and full warranty. I would probably go for that one instead of the TaoBao 7760B. Update 2: there seems to be a new revision of the MF-700F being sold with totally different modular cables /...
smallformfactor.net
The legit MF-600F should look pretty much the same internally as it's made by the same OEM, called "Extreme Cat" . You may check out their channel on BiliBili:
益衡金牌方案,且无电流声,全模组设计,稳定输出, 视频播放量 7281、弹幕量 4、点赞数 62、投硬币枚数 12、收藏人数 23、转发人数 5, 视频作者 极致猫电子, 作者简介 专注ITX电源,相关视频:蚂蚁悍将flex电源开箱拆解 ,是否是益衡方案?究竟抄走了多少作业?,极致猫7660b,益衡方案,通电是风扇位置火光四射然后就坏了。,机智猫 极致猫这电源你们还敢买了吗?...
m.bilibili.com
If you want to save money when buying a FLEX PSU just get a second hand / modded server PSU from a well known seller on taobao, like YTC for example.