Member Avatar for Ritesh_4

Hello.
I have a MB Asus P5B-VM, with 4 memory slots (dual channels). I already have a 2GB DDR2-800 RAM installed, and recently got 2 more RAMs, one a 2GB DDR2-800 same as my old one, and a 1GB DDR2-800. Can I install these 2 along side my old RAM?
The 4 slots are colored, with in A1 and A2 having yellow and black, and B1 and B2 having again yellow and black colored slots.
I would like to get confirmation before installing anything on it, just in case I might damage the whole thing with incorrect installs.

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Dani AI

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Brief expert note: dual‑channel works best when each channel contains matched memory (same capacity, similar timings/voltage). The colored slots mark channel pairs on a 4‑slot board such as the Asus P5B‑VM. Mismatched sizes or different SPD/voltage requirements can force single‑channel operation, produce asymmetric/flex behavior on some chipsets, or occasionally prevent POST. ’s stepwise swapping was the right diagnostic idea; ’s observation that the extra 1GB stopped the system while two matched 2GB sticks ran is consistent with either a compatibility issue, a bad DIMM, or a bad slot.

Quick, safe troubleshooting steps:

  • Power down, unplug, and discharge static before handling modules.
  • Test each DIMM alone in the primary slot and confirm the BIOS/POST reports its correct size; this isolates a bad stick or slot.
  • If each stick works alone, fit two identical modules in the recommended color pair for dual‑channel and verify stable boot.
  • If adding the third (1GB) causes POST failure, try that 1GB in every slot to rule out a bad slot. Clear CMOS after swaps if POST behaves oddly.
  • Consider a BIOS update only if stability/compatibility notes mention memory fixes.

Options and practical notes: to use the 1GB module reliably either obtain a matching 1GB so channels stay balanced, or keep the two identical 2GB sticks for stable dual‑channel performance. Some motherboards support an asymmetric/flex mode (matched portions in dual‑channel, leftover single‑channel) — check the manual/BIOS wording before relying on it.

Final tips: run memtest86+ after any successful boot to confirm stability. Persistent POST failures usually indicate an incompatible SPD/voltage, a defective DIMM, or a faulty slot; repeated trial-and-error is unlikely to damage the board, but pausing and replacing the problematic module or buying a matched pair is the pragmatic route.

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Member Avatar for rubberman

First, install the the 2GB DDR2-800 in the A2 slot (assuming the current one is in the A1 slot). See if that works. If so, then, install the 1GB SIMM in the B1 slot. If it doesn't work, install the 2GB SIMM in the B1 slot and try again... :-)

Member Avatar for Ritesh_4

thanks for the info, in the end I did put the 2nd 2GB in my B1 slot for it to work, with my initial 2GB in the A1 slot. As for the 1GB I've had to leave it out completely, since putting it in the A2 or B2 slots resulted in not going past the POST test.Think will need another 1 GB RAM to be able to use the one I already have.

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