Advice First Compact SFF build in a K39

[Waterrmelonn]

I'll be moving to another country to study in a few weeks, so I've decided to build a compact rig for when I'm there, although I'll mainly be buying and assembling the parts there.

I already have a gaming pc here, so I'll be transferring its cpu to my new build. My budget is pretty restricted, so here's what I've come up with:

Case: K39 from here: (https://www.aliexpress.com/item/4000333781136.html?spm=2114.12057483.0.0.4d5e7b98vOiIm6)
Motherboard: Asrock B550m itx/ac
CPU Fan: Noctua NH-L9A
GPU: Zotac GTX 1650 Super Twin Fan
Memory: Corsair 3600mhz ddr4
PSU: 1stplayer Flex 400w (Not sure about this, see below)

This is my first time building in SFF so I'm not sure about a few things:

1. Is the PCIE riser cable in the link compatible with the motherboard I've selected? Since the mb uses pcie 4.0
2. Has anyone else tried using that specific PSU? I've also thought about using the enhance ENP-7660p but that seems like overkill for my build.

Thank you all for your help!

 

[rfarmer]

Your motherboard is PCI 4.0 but your GPU is PCI 3.0 so the riser card will work at 3.0, they are backward compatible. Your motherboard will automatically detect a 3.0 GPU.

 

[Waterrmelonn]

Your motherboard is PCI 4.0 but your GPU is PCI 3.0 so the riser card will work at 3.0, they are backward compatible. Your motherboard will automatically detect a 3.0 GPU.

Thanks! On that note, would you recommend any particular psu for this case?

 

[rfarmer]

Sorry I don't personally have any experience with Flex PSUs.

 

[n.tesla]

2. Has anyone else tried using that specific PSU? I've also thought about using the enhance ENP-7660p but that seems like overkill for my build.

You want overkill. All these 1U PSUs are built for servers that will invariably be sat in a wind tunnel of noise and airflow locked away in a room far away from human ears. End result is, they are LOUD but only when the fan actually kicks in. Since the PSU is likely rated for double of what your system will actually draw then the fan will remain mostly silent as demonstrated in this graph: https://pictr.com/images/2019/06/07/50g5uJ.jpg