Question My pc suddenly black screen and PSU keep make on and off sound, what's wrong with my PC?

[shideichis]

My pc parts:

• CPU: AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor
• CPU fan: be quiet! Pure Rock 2 CPU Cooler
• Motherboard: MSI B650 GAMING PLUS WIFI ATX AM5 Motherboard
• RAM: Corsair Vengeance 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory
• Storage: Samsung 980 Pro 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
• Video Card: ASRock Challenger Pro OC Radeon RX 6750 XT 12 GB Video Card
• PSU: MSI MAG A750GL PCIE5 750 W 80+ Gold Certified Fully Modular ATX Power Supply
• Case: Phanteks G300A ATX Mid tower case (with 3 fans installed)

Everything was fine after I built it a week ago. I was able to install Windows 11 through a bootable USB. I even set up and installed everything on my Windows, and I was able to play games from Steam for a couple of days.

But then yesterday, while I was playing a game, my screen went black. I noticed the EZ LED was flickering on GPU and BOOT, while CPU and DRAM were steady, and there was a flickering sound coming from my PSU that was turning on and off repeatedly.

I turned it off and unplugged everything from the motherboard, then installed each part one by one, while still connecting the POWER_SW from the case to the motherboard (case fan not connected).

• With the CPU and CPU fan installed and the PSU on, the CPU fan was running, and the EZ LED was on for CPU and DRAM.
• When I installed the RAM (I had 2 sticks, tried one by one), the CPU fan was still running with the PSU on, and there was no change in the EZ LED, which remained on for CPU and DRAM.
• When I installed the SSD, the issue appeared. With the PSU on, the EZ LED for GPU and BOOT continuously flickered, and the PSU failed, making a clicking sound repeatedly turning on and off.

I also tried connecting just the motherboard, CPU, RAM, and case I/O (3 fans, audio, and power). When the PSU was on, 2 of the 3 fans turned on, and later only the top fan remained on. This didn’t cause the PSU to turn on and off, but the motherboard's EZ LED for GPU and BOOT flickered.

I also tried updating the BIOS, as I hadn't done it before, using Flash BIOS with version 7E26v19, and it was successful.

I'm not sure if the combination of my ARGB fan case, SSD, and motherboard is causing the black screen
What should I do?

 

[Paperdoc]

This MIGHT be a case of an intermittent short causing PSU overload. ONE way that can happen with a new built-it-myself case is NOT having the mobo stand-offs positioned correctly. If you already know about that, ignore this idea. But if you need full details so you can check for sure, post back here.

 

[shideichis]

Hello thanks for your reply.
I’m not very familiar with standoffs and how they should be used. I checked the case guide, but it only mentions that they provide 1 standoff tool and 1 MB standoff tool without any detailed instructions on their placement or usage so I didn't use it.

Could you please explain what do you mean?

 

[Paperdoc]

In mounting the mobo to the back support plate of your case, there are small stand-offs used between the back plate and the mobo. Typically these are metal items about ¼" long with a threaded shaft out of one end and a threaded hole at the other. Each screws into a threaded hole in the case back plate, giving you a new threaded hole on top into which you use screws through mounting holes of the mobo. Some cases come with these stand-offs pre-installed in back plate holes, but some provide them in a bag and they need to be installed.

All mobos have mounting holes - very often nine as three rows of three. Look closely at them and you'll see that each has tiny metal "fingers" around it. It is intended that the mobo will be Grounded to the case by the screws through these holes into the metal stand-offs. But these and the power supply connectors are the ONLY places that the mobo should make contact with the case metal. So it it IMPORTANT that the stand-offs be placed exactly where the mobo mounting holes are and none anywhere else. If they came loose in a bag they all need to be placed by you. If they were pre-installed, you need to re-examine them carefully. One or more may be installed in a back plate hole that is NOT aligned with a mobo mounting hole. If that happens the misplaced stand-off needs to be moved to a correct location. The case back plate has many more threaded holes for stand-offs so the locations can be adjusted for each mobo.

Make sure your system is unplugged from the wall. You will need to remove the mobo from the case (or at least remove all its mounting screws to loosen it). Examine each mounting hole in the mobo and the corresponding stand-off under it. Ideally there ought to be a stand-off under each mounting hole for support. It is IMPORTANT that there be NO stand-off anywhere that does NOT line up exactly with a mobo mounting hole. Any such unit can touch bare traces on the bottom of the mobo and create a short circuit, often as an intermittent contact. If you move one, re-position the mobo and check carefully that ALL stand-offs are directly under a mounting hole, and NONE are in a place under NO mounting hole. Once you are SURE that all the stand-offs are positioned properly you can postition the mobo on them and re-install all its mounting screws.

 

[shideichis]

yeah the standoff on the case is aligned with the screw holes on the motherboard

 

[shideichis]

Also tried unmount motherboard from case and

• only installed CPU + RAM, debug led on for CPU and DRAM, no on and off from PSU
  
  
• only installed CPU + RAM + ssd nvme, debug lead same on for CPU and DRAM
  
  

 

[Paperdoc]

When you test out of the case, you need to install in the mobo at least:
CPU
One stick of RAM (could be more)
CPU cooler system attached to the CPU_FAN header - it will NOT try to start up if there is NO CPU cooler speed signal at that header

That should allow it to start and complete the POST process. The signal of success - IF your mobo has a "beeper" so make basic sounds - would be a single beep at the end of POST.

If that appears to work, you might connect a monitor to your video output (from the mobo or by adding a video card in a PCIe slot) and re-ding the start-up to look for messages on the monitor.

Your post above does no indicate you had a CPU cooler atttached.

 

[shideichis]

I already tried with the CPU cooler attached and the cable connected to the CPU_FAN header on the motherboard, as well as one stick of RAM. Unfortunately, there was no change; the lights for the CPU and DRAM remained steadily on.
And still black with display