Build Advice PC chooses when it wants to turn on ?

[Watame]

Hello, I recently upgraded my old pc to a new pc but after switching the parts around, turning the pc on becomes a gamble.

At first I bought a 3070ti and a ryzen 5 5600x and replaced my old 1050ti and ryzen 5 2600, everything was running fine and all was working.

Then I purchased a new case for better airflow along with 6 fans and a new cpu cooler as the ryzen 5 5600x was running really hot (peaked 97.5°C).

(Day 1) Changed the case from a CM Masterbox 5 lite to a Lianli lancool II Mesh along with come psu cable extensions and 6 MF120 from coolermaster, and after assembling, it didnt work so I swapped out the 5600x and placed in the 2600 and it powered on. I then brushed the 5600x pins to make sure nothing is in the way of the pins and placing it back in the pc, it powered on.

(Day 2) However on the next day, the pc powers on with mobo and gpu lights all on, but no display on the monitor. Naturally, I took the old 2600 and placed it back in, but nothing changed. No display but all lights on.

(Day 3) The next day I went to take all my parts out and placed the b450 motherboard, the 3070ti and the 5600x with the corsair vengeance ram all together and boom. It powers on again. Nothing changed at all, just placed it back and it worked.

(Day 4) THE VERY NEXT DAY, it doesn't power on again. So I went to buy a new b550 motherboard since I needed to have 2 pcs anyway so I went home to test out the mobo and BOTH the b450 and b550 powered on fully to windows with only the 2600 and not the 5600x.

(Day 5) I went to a local pc repair shop and brought both the 2600 and 5600x, the b450 and b550, my ram, the 3070ti and the old psu. After testing, the technician told me that my psu was failing and every other part was working (GPU, B450, B550, 2600, 5600x, ram and he even showed me that it powers on to bios) so I bought a brand new psu (Superflower LEADEX III 80+ gold), went home and built my pc again back in the case. The only the ryzen 2600 worked on both mobos. With the 5600x placed in it, it completely doesn't power on, no lights nothing. So I thought yeah CPU probably died. So I just used my PC to game and was going to rma the 5600x.

At night when I wanted to turn my PC off, I shutdown windows as per usual but after my monitor went black and waiting at least 3 minutes for my pc to power off, it doesn't. The fan and gpu lights were still on, so I force shutdown the pc by turning the outlet switch off and I tried to power it on again but to no avail.

(Day 7) Today in the morning the PC still doesn't power an and I really do not know what to do.
Changed GPU, CPU, motherboard and PSU

Old pc specs:
CM Masterwatt 650 80+ bronze
Corsair Vengeance LPX 2666
MSI B450 Tomahawk
Ryzen 5 2600
Asus 1050ti pheonix
CM Masterbox lite 5
Samsung EVO 860
Phison 512GB NVMe SSD

New pc specs:
Superflower LEADEX III 80+ gold
Corsair Vengeance LPX 2666 (Same as old)
MSI B550 Gaming edge wifi
Ryzen 5 5600x
Asus ROG strix 3070ti OC
Lianli lancool II Mesh RGB
Samsung EVO 860
Phison 512GB NVMe SSD

The 6 Fans used were CM mf120 and the new cpy cooler is the deepcool AK620

 

[Cyberat_88]

I am starting to get the idea that the Lianli lancool II Mesh case has bad switches/connectors.
Other than that my first check would be - Does either MB support the Ryzen 5 5600x out of the box or need a bios update ?
Second guess would be that the Superflower is a junky cheap, bad selection PSU and is failing like your old one (no Watt specs.).
I suggest a nice Corsair RM 850 Gold like mine. But I maybe biased, CM, Antec, EVGA are all known good & reliable brands too.
Cannot go wrong with having more power than you need, than thinking you have enough and not have it.