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1. System Won’t Boot (Or Stuck in a Boot Loop)
A non-booting system doesn’t always mean catastrophic hardware failure. You’re often dealing with one of three domains: power delivery, firmware/BIOS, or storage/OS.
Initial hardware and power checks
**Verify power delivery**
- For desktops, confirm the PSU’s rear switch is set to `I` (on), not `O`. - Check power strip or UPS is active; test the outlet with another device. - Reseat the power cable in both the PSU and wall outlet.
**Look for POST indicators**
- Observe power LED, drive activity LED, and listen for beep codes. - Many motherboards have debug LEDs (CPU/DRAM/VGA/BOOT). Note which stays lit. - Consult your motherboard or system maker’s manual to interpret codes.
**Minimal boot / POST test**
- Power off and unplug the system. - Remove all non-essential devices: extra HDDs/SSDs, USB drives, external peripherals, and add-in cards except GPU (if no integrated graphics). - Reseat RAM (try booting with a single stick in the primary slot). - Try integrated graphics (if available) by removing the discrete GPU and connecting your monitor to the motherboard video output.
Firmware and boot configuration
**Access UEFI/BIOS**
- Spam `Del`, `F2`, `F10`, or `Esc` immediately after powering on. - Verify the primary drive (SSD/HDD) is detected under “Storage” or “Boot” settings. - Ensure the correct drive is first in the boot order; disable unneeded PXE/network boot if it’s taking priority.
**Repair boot loader and OS startup (Windows)**
- Boot from a Windows installation USB. - Choose **Repair your computer → Troubleshoot → Advanced options**. - Use **Startup Repair** first; if that fails, open **Command Prompt** and run: ```cmd bootrec /fixmbr bootrec /fixboot bootrec /scanos bootrec /rebuildbcd ``` - Reboot and test.
When to suspect disk failure
If the drive is intermittently detected, makes clicking sounds, or shows up with incorrect capacity in UEFI/BIOS, treat it as a potential failure. Stop repeated power-cycling and, if data is critical, prioritize data recovery before further experiments.
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2. System Is Slow, Freezing, or Stuttering Under Load
Sluggish performance often traces back to three main constraints: storage (I/O), RAM pressure, or thermal throttling. Diagnosing correctly avoids blindly “upgrading hardware” that isn’t the true bottleneck.
Check resource utilization
**Windows Task Manager / Linux tools**
- Windows: `Ctrl + Shift + Esc` → **Performance** tab. - Observe CPU %, Memory usage, Disk usage, and GPU if applicable. - Linux: use `htop`, `top`, `iotop`, or `glances` to watch utilization.
**Identify problematic processes**
- Sort by CPU and disk usage; note any process that stays pegged at high utilization. - For browsers, many tabs or hardware-accelerated content (video, WebGL) can spike CPU/GPU.
Storage and OS health
**Check for SSD/HDD issues**
- Excessive 100% disk usage with low throughput can indicate failing drives or driver issues. - Run SMART diagnostics: - Windows: `wmic diskdrive get status` (very basic) or third-party tools that read SMART data. - Linux: `sudo smartctl -a /dev/sdX`. - If reallocated sector count or pending sectors are rising, plan for drive replacement and backup immediately.
**Minimize startup and background load**
- Windows:
- `Ctrl + Shift + Esc` → **Startup** tab, disable non-essential entries (game launchers, vendor updaters, etc.).
- In **Settings → Apps → Installed apps**, uninstall toolbars, bundled OEM utilities, or “optimizer” tools that constantly run.
- macOS: **System Settings → General → Login Items**, remove unneeded background apps.
Thermals and throttling
**Monitor temperatures and clocks**
- Use vendor tools (e.g., Intel XTU, AMD Ryzen Master) or third-party monitoring (HWInfo, lm-sensors on Linux). - CPU temperatures consistently above 90–95°C under moderate load suggest cooling issues.
**Improve cooling and airflow**
- Power down, unplug, and remove side panel (desktop) or access panel (laptop, if permitted). - Carefully blow out dust from fans and heatsinks using compressed air (short bursts; keep fan blades from overspinning by holding them still). - Ensure front intake and rear/top exhaust fans create a clear airflow path. - Replace dried or poorly applied thermal paste on CPU/GPU if temps remain high and you’re comfortable with hardware work.
If performance improves dramatically after cooling adjustments, you were likely hitting thermal throttling rather than “needing more RAM or a faster CPU.”
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3. Random Crashes, Blue Screens, or Spontaneous Reboots
Unpredictable crashes are often tied to memory instability, power problems, or driver issues. Instead of reinstalling everything immediately, collect clues.
Collect error information
**Note error messages and codes**
- Windows BSODs show a stop code such as `MEMORY_MANAGEMENT`, `IRQL_NOT_LESS_OR_EQUAL`, or `VIDEO_TDR_FAILURE`. - Use **Event Viewer** (`eventvwr.msc`) → **Windows Logs → System** to spot “Critical” events (Kernel-Power, BugCheck).
**Check power stability**
- Unstable or undersized PSUs can cause reboots under load (e.g., gaming, rendering). - If crashes only occur when GPU is under heavy load, suspect PSU or GPU drivers.
Test memory and storage
**Run memory diagnostics**
- Windows: **Windows Memory Diagnostic** (`mdsched.exe`) → “Restart now and check for problems.” - For deeper testing, use MemTest86 from a bootable USB and perform multiple passes. - If errors appear, test each RAM stick individually and each slot; faulty DIMMs or slots must be replaced or avoided.
**Check system files (Windows)**
- Open an elevated Command Prompt and run: ```cmd sfc /scannow DISM /Online /Cleanup-Image /RestoreHealth ``` - `sfc` scans and repairs corrupted system files; `DISM` repairs the underlying component store.
Driver and firmware stability
**Update or roll back drivers**
- GPU: Download the latest stable WHQL driver from NVIDIA/AMD/Intel, perform a clean install. - Chipset and storage drivers: Get them from your motherboard or system vendor’s support site. - If crashes began immediately after a driver update, roll back in **Device Manager → Properties → Driver → Roll Back Driver** (if available).
**Update UEFI/BIOS carefully**
- Check your motherboard or OEM support page for newer firmware that addresses stability or memory compatibility. - Use the recommended flashing tool (e.g., built-in UEFI flash utility). - Avoid flashing during storms or on unstable power; a failed flash can brick the motherboard.
If crashes persist after memory checks, storage checks, and driver/firmware updates, suspect deeper hardware issues (motherboard, CPU, or GPU) and consider professional diagnostics.
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4. No Network, Unstable Wi‑Fi, or DNS Errors
Network issues can appear as “the internet is down,” but the fault can be at multiple layers: physical, IP configuration, DNS, or router/ISP side.
Local checks first
**Confirm physical connectivity**
- For Ethernet, check link LEDs on the NIC and router/switch port. If no light, test with another cable and port. - For Wi‑Fi, ensure the adapter is enabled: - Windows: **Settings → Network & Internet → Wi-Fi** (toggle on). - Check for physical wireless switch or function key on some laptops.
**Check IP address and basic reachability**
- Windows: open Command Prompt and run: ```cmd ipconfig /all ``` - Confirm you have a valid IPv4 address (not `169.254.x.x`). - Test local gateway reachability: ```cmd ping 192.168.0.1 ping 192.168.1.1 ``` (Use your actual gateway from `ipconfig`.)
Resetting stack and DNS
**Reset TCP/IP stack (Windows)**
Run Command Prompt as Administrator and execute: ```cmd netsh winsock reset netsh int ip reset ipconfig /release ipconfig /renew ipconfig /flushdns ``` Reboot and test connectivity afterward.
**Test DNS separately from connectivity**
- Try pinging a public IP:
ping 8.8.8.8
If this works but `ping google.com` fails, DNS is the problem, not the underlying connection.
- Temporarily set a known DNS server:
- Windows: **Control Panel → Network and Internet → Network Connections → Adapter Properties → Internet Protocol Version 4 (TCP/IPv4)**
- Set DNS to `8.8.8.8` and `1.1.1.1`, then test again.
Router/ISP and interference
**Isolate router or ISP issues**
- Reboot modem and router (power off for 30 seconds, then power on modem, wait for full sync, then router).
- Test another device on the same network. If all devices fail, suspect router/ISP.
- Connect one device via Ethernet directly to the modem (if your ISP allows) to isolate router issues.
- Check signal strength; aim for at least -67 dBm or better for stable video calls/streaming.
- Avoid congested channels: use the router admin interface or Wi‑Fi analyzer tools to pick a less crowded channel (1, 6, or 11 on 2.4 GHz; any clean channel on 5 GHz).
- Move the PC or router to reduce obstructions (metal shelving, concrete walls, large appliances).
**Optimize Wi‑Fi signal quality**
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5. Display Problems: No Signal, Artifacts, or Flickering
Display failures can stem from the monitor, the cable, the GPU, or the OS-level configuration. Systematically swapping components and checking settings avoids guesswork.
Baseline checks
**Verify monitor power and input**
- Ensure the monitor is powered on and not in a deep sleep mode. - Use the monitor’s OSD (on-screen display) to confirm the correct input (HDMI1 vs HDMI2 vs DisplayPort, etc.). - Test the monitor with another device (a laptop or console) to see if it displays a signal.
**Inspect and test cables**
- Reseat both ends of the cable. - Try a different cable and, if possible, a different connector type (e.g., DisplayPort instead of HDMI). - Avoid adapters and dongles until a direct connection has been tested.
GPU and firmware checks
**Switch between integrated and discrete graphics**
- If your CPU and motherboard include integrated graphics, remove the dedicated GPU and plug the monitor into the motherboard output.
- If video works via integrated graphics but not the GPU, suspect GPU failure, power delivery, or driver issues.
**Safe Mode and basic resolution resets (Windows)**
- Boot into **Safe Mode** (hold `Shift` while clicking Restart → Troubleshoot → Advanced options → Startup Settings → Restart → choose Safe Mode). - Safe Mode uses a basic display driver; if the display is stable there, the problem is likely GPU driver or a bad custom resolution/refresh setting. - In Safe Mode, uninstall the GPU driver via **Device Manager**, then reboot and install the latest stable driver from the GPU vendor.
Artifacts, lines, and intermittent flicker
**Distinguish software vs hardware faults**
- If artifacts (random colored blocks, lines) appear in UEFI/BIOS or during boot logos, it’s generally a hardware issue (GPU or monitor), not the OS.
- If artifacts only appear in 3D applications or games, stress test the GPU with tools (e.g., vendor diagnostics) while monitoring temperatures.
- Excessive GPU temps (80–90°C+) and crashes under load suggest cooling or power issues.
- Set resolution and refresh rate within both GPU and monitor capability:
- Windows: **Settings → System → Display → Advanced display**.
- Avoid experimental custom timings until baseline stability is confirmed.
- For high-refresh monitors (144 Hz+), confirm you’re using a cable and port that supports the required bandwidth (e.g., DisplayPort 1.4 or HDMI 2.0+).
**Refresh rate and resolution sanity check**
If display issues persist after these steps, capture photos or videos of the artifacts or failure state; they can be very useful when consulting with support or a repair technician.
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Conclusion
Most PC problems can be broken down into a few predictable domains: power, thermals, memory, storage, network, and display path. By systematically isolating each layer—starting with the physical connections, moving through firmware and drivers, and only then targeting the OS—you dramatically increase your chances of a clean, quick fix with minimal disruption. Use these five troubleshooting workflows as starting blueprints, adjust for your specific hardware and OS, and always treat backups as non-negotiable whenever you suspect failing storage or repeated instability.
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Sources
- [Microsoft Support – Troubleshoot blue screen errors](https://support.microsoft.com/en-us/windows/troubleshoot-blue-screen-errors-5a9af9e5-0e98-4b02-ae15-33328c4fc5f2) - Official guidance from Microsoft on interpreting and resolving BSODs
- [Intel – Troubleshooting Windows Performance Issues](https://www.intel.com/content/www/us/en/support/articles/000057396/processors.html) - Covers CPU, thermal, and performance-related troubleshooting on Windows systems
- [NVIDIA – Troubleshooting Graphics Issues](https://nvidia.custhelp.com/app/answers/detail/a_id/3103) - Vendor documentation on resolving common GPU and display problems
- [Federal Communications Commission (FCC) – Interference with Wi-Fi and Other Wireless Networks](https://www.fcc.gov/general/interference-facts) - Explains wireless interference sources and mitigation, relevant to Wi‑Fi stability
- [MemTest86 – User Guide](https://www.memtest86.com/tech.html) - Technical reference on using MemTest86 for detecting memory errors and instability