Blackscreen and reboots for seemingly no particular reason

Troubleshooting Unexpected PC Freezes and Reboot Cycles on a Custom-Built System

Building a custom PC can be an exciting experience, but it often comes with its own set of challenges. Recently, a user shared a common yet perplexing issue: their computer would randomly freeze and then reboot without warning, leaving no clear error messages. Here, we explore this problem in detail, discuss potential causes, and suggest troubleshooting steps to help you diagnose and resolve such symptoms.

Understanding the Issue

The user previously faced difficulties booting into Windows 10, which has since been resolved, allowing access to the desktop. However, approximately 30 minutes into usage, the system unexpectedly freezes, then powers off entirely. After the shutdown, the PC automatically restarts, but no specific error messages appear; the only entries logged are Kernel-Power errors, typically indicating improper shutdowns.

System Specifications

CPU: AMD Ryzen 7 3700X
Motherboard: MSI MAG B550 Gaming Plus
Graphics Card: Asus GeForce RTX 4060
Storage: Seagate Barracuda 2TB HDD, WD SN770 500GB M.2 SSD
RAM: 2x 16GB Teamgroup T-Force Vulcan Z DDR4 3600 MHz
Power Supply: be quiet! Pure Power 12 M 750W

While these components are generally reliable, intermittent shutdowns can stem from various hardware or software issues.

Potential Causes and Diagnostic Considerations

Temperature Concerns

Although overheating is a common cause of system instability, the user suspects temperature isn’t the problem, citing stable thermal performance. Nevertheless, it is advisable to monitor CPU and GPU temperatures during operation using tools like HWMonitor or MSI Afterburner. Even if temperatures seem normal, confirming this can help rule out thermal throttling or overheating.

Power Supply and Power Delivery

A failing or underperforming power supply can cause abrupt shutdowns. Despite the 750W PSU being sufficient for this build, quality issues or aging components may lead to inconsistent power delivery. It’s noteworthy that the PC is connected to a power strip sharing a socket with other devices, including a Wi-Fi modem. However, if the circuit breaker isn’t tripping, this likely isn’t the cause. Still, testing the system with a different power outlet or a known-good power strip can help eliminate power supply as a culprit.