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PC won't POST when I have both Ram Sticks installed (each work when installed individually)

Hi! I'm currently trying to get the most use out of an oldish machine.

OS: Win7 64bit
MoBo: Asus P5KPL-AM EPU
CPU: Intel Core 2 Duo E8200, 2.67 GHz

The MoBo has 2 slots for DDR2 Sticks (both colored yellow). I checked the manual, and there doesn't seem to be any needed order when installing. It allows up to 4GB.

When I bought this old machine, it already had a 2GB stick installed, a Kingston 800/PC2-6400 KVR800D2N6/2G

I was able to find another 2GB stick, a Samsung M378T5663EH3-CF7 800

I don't have the packaging for both sticks, so I had to go by research based on serial#s, but as far as I can see, both sticks have the same speed (don't know how to check for CAS Latency... does that matter?)

When I check using CPU-Z, it's weird since although I only have 1 stick installed, CPU-Z says that I have 4GB, and the current stick appears for both DIMM1 and DIMM2 (also, "both" are running at 400MHz)

Anyway, when I put both sticks in, my PC wouldn't go to POST. I tried each stick individually on DIMM1, and the system loaded without any problems... I haven't checked yet if putting a single stick on DIMM2 will work, but I assume that it will (if the slot is really busted, then wouldn't the system not be able to detect anything there, so it would still boot normally, right?)

Any idea what I can do?

Thanks!
3 answers Last reply Best Answer
More about post ram sticks installed work installed individually
  1. UPDATE: I was able to resolve the issue simply by resetting the CMOS battery. It seems like there might have been some configuration settings and/or errors on the chipset.
  2. Best answer
    Read up on the specs for the memory - they seem to be identical - DDR2 SDRAM, 2GB, 240-PIN, PC-6400, Non-ECC, Cycle time 5ns, CAS CL6, Data Transfer Rate 800Mhz, memory clock 200Mhz, and Voltage 1.8V.

    The only thing I found different was in the description of the memory - the Kingston was "Dual Rank Memory Module", where the Samsung was "Memory Module" (no dual-rank).

    The mobo is dual-channel - and specs line up. Found ratings on the Samsung Memory:
    266MHz @ 4-4-4-12-16, 1.80v
    333MHz @ 5-5-5-15-20, 1.80v
    400MHz @ 6-6-6-18-24, 1.80v
  3. to make them work you must align them to the exact voltage, speed and cl timings and you got to do it manually the is no other way. basically you have to lower the specs of the faster one.maybe the will(work) maybe not. thats why memory is sold on pairs
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