Problems with pre-boot on Dell Optiplex 7040.
Problems with pre-boot on Dell Optiplex 7040.
Details: Core i5-6600, 16GB DDR4, 2400MHz RAM, Samsung Evo 970 M.2 1TB, Windows 10 installed. Uses 240W PSU from EVGA GTX 1050 TI SC OEM. When power cuts out or I disconnect the cord after AC restarts, the system tries to restart three times. It retries booting or enters setup when a pre-boot error appears about missing BIOS date/time. It also attempts to boot automatically on its own even though that setting is disabled in BIOS. After fixing, it boots normally each time. I’ve replaced the CMOS battery. Next, I’m considering swapping the OEM power supply. Hopefully it’s not a motherboard problem. Both parts are reasonably cheap on eBay.
This setup is quite old. Consider swapping the battery—possibly a wired one. The core remains the same, but it needs to read above 3V to function correctly. A fresh unit should provide 3.3V. Also verify if it connects to the BIOS reset pins, which I've noticed in some Dell models before.