Symptoms
- System reports less RAM installed than what's physically present
- One or more sticks don't show up in BIOS at all
- PC won't boot at all with certain RAM configurations
- Problem started after installing new memory or moving the PC
Likely causes
- CommonRAM stick not fully seated in its slotMemory needs to click firmly into place on both sides.
- CommonRAM installed in the wrong slots for the intended configurationMotherboards often require specific slot pairs for dual-channel setups.
- PossibleIncompatible or unsupported RAM speed/type for the motherboardVery high-speed or unusual RAM may need a BIOS update or isn't supported.
- PossibleFaulty RAM stickA single bad stick can prevent detection even when others in the same system work fine.
- PossibleOutdated BIOS lacking support for newer memoryThis especially affects very new RAM kits on older motherboards.
What to do
- Power down, unplug, and reseat each RAM stick fully until both side clips click into place.
- Check the motherboard manual for the correct slots to use for the number of sticks installed.
- Try each stick individually in the primary slot to identify if one specific stick is faulty.
- Check the motherboard manufacturer's website for a BIOS update, especially with newer or higher-speed RAM.
- Confirm the RAM is on the motherboard's supported/tested memory list if available.
- If a specific stick never gets detected in any slot, treat it as faulty and consider a replacement or warranty claim.
Tools and parts
- Anti-static precaution
When to call a pro
If reseating and slot changes don't resolve it and you suspect a motherboard compatibility issue, a technician can test the RAM in a known-working system to confirm.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.