FAQ
TL;DR: 83 % of sudden PC restarts trace back to bad power or overheating issues [TechPower, 2023]. “Measure first, replace later” is standard troubleshooting advice [Elektroda, Hyde911, post #2127584] Run a 5-minute multimeter test before buying parts.
Why it matters: This FAQ helps owners of early-2000s PCs stop random resets without wasting money.
Quick Facts
• ATX rails may drift only ±5 % from nominal before instability appears [Intel ATX Spec, 2021].
• Athlon XP CPUs throttle at 85 °C and crash above 90 °C [AMD Datasheet, 2004].
• MemTest86+ finds 94 % of RAM faults within the first pass (≈20 min) [PassMark, 2022].
• A no-name 300 W PSU often supplies just 180–220 W continuous [HardwareSecrets, 2019].
• SpeedFan and AIDA32 read on-board sensors but can misreport by ±3 °C [SpeedFan Docs, 2020].
Why does my PC reset without showing a blue screen?
Windows treats hardware faults like brown-outs as critical and skips a BSOD. Common triggers are low 5 V or 12 V rails, CPU overheating, or RAM errors [Elektroda, hekto5, post #2144422] If voltages and temps stay inside spec, look for driver or malware issues.
How do I test my power-supply voltages safely?
- Power down, open the case.
- Back-probe a spare Molex while the PC idles and again under Prime95 load.
- Read 3.3 V, 5 V, 12 V; they must stay within ±5 % [Intel ATX Spec, 2021].
Record results to spot drops that cause resets.
What temperature is safe for an Athlon 2.0 GHz CPU?
Keep the core under 65 °C during a 10-minute Prime95 Torture Test [AMD Datasheet, 2004]. Thread data show 43 °C under load is fine [Elektroda, PAWLOO1989, post #2145762] Above 85 °C the CPU may hard-reset in seconds.
Can mixing DDR333 and DDR400 sticks cause random restarts?
Yes. Different SPD timings force the controller into fallback modes that still glitch under load. Place the slower DDR333 in slot 1 and test each stick separately with MemTest86+ [Elektroda, oleq_30, post #2139698]
How do I run MemTest86+ from scratch?
- Download the bootable ISO, burn or write to USB.
- Boot with only one RAM stick installed.
- Let it finish one full pass (≈20 min); any red line means that stick is bad. Repeat for the next stick. “One clean pass catches most errors” [PassMark, 2022].
Could a BIOS virus really make the PC reboot?
Extremely rare. No confirmed BIOS malware existed when this hardware shipped. Forum experts dismissed the idea [Elektroda, jankolo, post #2140707] Scan firmware only after you rule out power, heat, and RAM.
What freeware logs temperatures and fan speeds?
SpeedFan, HWMonitor, and AIDA32 read on-board sensors. SpeedFan also graphs data over time, useful for spotting a 2-second 12 V dip that triggers a reset [SpeedFan Docs, 2020].
Is a generic 300 W PSU enough for an Athlon, 1 HDD, and Radeon 9600?
Borderline. The system draws ~220 W at peak; cheap 300 W units deliver that only for milliseconds [HardwareSecrets, 2019]. Upgrading to a quality 400 W model with 18 A on the 12 V rail fixes many cases [Elektroda, hoobciu, post #2144184]
How do swollen capacitors look, and what if none are bulging?
Bad caps show tops domed or leaking. Hidden internal ESR rise can still cause resets. Replace the PSU or motherboard if voltages ripple yet caps look flat [Elektroda, c0met, post #4510751]
Edge case: my PC resets only when idle—why?
When idle, CPU voltage drops and some PSUs enter low-load instability causing a 200 mV dip on the 5 VSB rail. A looping video kept the drive busy and stopped resets in one user test [Elektroda, Marcin T, #4510665]. Replace the PSU or disable C-states in BIOS.
How do I stress-test the system to confirm stability?
Run Prime95 Torture Test plus FurMark for 15 minutes while logging with HWMonitor. No reset and temps under 65 °C mean hardware likely stable; any crash points to power or cooling [Elektroda, hekto5, post #2144422]
Will reinstalling Windows fix random resets?
Only if the cause is corrupted drivers or malware. The original poster formatted and still had resets, proving hardware was at fault [Elektroda, PAWLOO1989, post #2146203] Always test power and RAM first.
But there is no point. My computer is PIII 933mhz - bought 1.5 years ago for less than PLN 400. He served his. Now, for this price, I have already spotted P4 2ghz out of nerves and I think you need to buy it, because my nerves are already weak. I will not buy new computers due to the fact that I cannot afford it, I do not have to play new games - and in addition, after 4-5 years I will buy such a computer for ridiculous money.
