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cptrstuff 0 Newbie Poster

Sad to say I found that my daughter had added DDR1 memory from her old computer to DDR2 memory in her new computer-- this is a big no-no. Different number of pins on the two types of memory.

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Dani AI

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Good catch, . DDR (desktop 184-pin) and DDR2 (desktop 240-pin) modules are keyed differently and run at different signaling voltages, so they are not cross-compatible. If a board has both DDR and DDR2 slots, you still cannot use both types at the same time; trying to do so will usually prevent POST, which looks like fans spinning but the monitor saying No Signal (DDR SDRAM, DDR2 SDRAM).

Quick recovery checklist:

  • Power off, unplug, hold the power button 10 seconds to discharge.
  • Remove all RAM. Inspect slots for cracked plastic or scorch marks (if a stick was forced in, the socket may be damaged).
  • Install only one known-good DDR2 module in the primary slot (often A1). Try other slots if no POST.
  • Clear CMOS to reset memory training (use the CLR_CMOS jumper or temporarily remove the CR2032 battery with power unplugged).
  • If there is a case speaker, plug it in and listen for POST beeps; continuous or repeating beeps typically indicate a memory problem. Beep patterns vary by BIOS vendor (Beep codes, Power-on self-test).
  • Reseat the graphics card and its PCIe power leads (if present). If the motherboard has integrated video, move the display cable there to test.
  • Try a different cable/port on the monitor to rule out a bad connection.

If it boots with a single DDR2 module, add additional DDR2 sticks one at a time and retest. Mix-and-match within the same DDR generation is usually OK, but the system will run at the slowest module’s speed, and unstable pairs should be avoided. If there is still no POST with proper DDR2 installed, the forced mix may have damaged a slot or the board, in which case testing with a different motherboard or known-good RAM/CPU is the next step.

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