Problem with RAM upgrade on ASUS MB

[DimPas]

I have an ASUS A7N266-C motherboard with 256 MB installed RAM.
I just wanted to upgrade to 1.25 GB, so I bought 2 DIMMs Kingston KVR266X64C25/512, CL2.5, PC2100, 2.5 volts, fully compliant with the system.

I installed the DIMMs as instructed in the manual, i.e. the 2 Kingston 512MB in slots DIMM1 and DIMM2 and the third one, a 256MB DIMM into the DIMM3 slot. The 3 DIMMs have a total of 5 banks as instructed by the MB manual.

I started the system, but there was only the alarm signal, indicating that no DIMMs were recognized. When I removed the DIMMs2 and 3, letting in only the DIMM1 the system started up, but the BIOS setup was launched with the CPU/PCI Frequency (MHz) in bold (the value stored was 100/33). On the right there was the following message: "During the last bootup, your system hung for an improper CPU speed setting.Your system is now working in safe mode. To optimize the system performance and reliability, make sure the CPU speed conforms to the specifications of your CPU".

Conlclusion:The system works properly when the DIMM1 only slot is occupied (either with 256MB or 512 Mb chips).Otherwise it hungs, with the message above. Pls note that I have an AMD Athlon XP 1800 CPU. The system dates back to 2002.

Please provide me with necessary directions.
Thank you so much.
Dimitris

 

[colt1911]

Can you put one stick of 512 in and get to the Bios and set the memory voltage to 2.5 volts? Also you might want to read this (http://www.memory-up.com/Memory/AsusA710091_512MB333MHz.html?utm_source=Froogle&utm_medium=referral ).

 

[DimPas]

Can you put one stick of 512 in and get to the Bios and set the memory voltage to 2.5 volts? Also you might want to read this (http://www.memory-up.com/Memory/AsusA710091_512MB333MHz.html?utm_source=Froogle&utm_medium=referral ).

Actually I cannot change the RAM voltage through teh BIOS only through the jumber onboard.

 

[PC eye]

The problem isn't the voltage setting but the front side bus setting. Obviously the 256mb dimm is slower memory and conflicting with the faster memory. Try running just a 512 to lower the fsb(memory clock) down a notch to see if the system then sees a normal boot.

 

[DimPas]

I've run the system with only one 512, CPU/PCI bandwidth set to 133/33, thus having a CPU speed 11.5 x 133 = 1.53GHz, mbut again no luck at startup. Should I consider a BIOS update?

 

[PC eye]

It won't hurt to see the latest update go on. Are all 3 dimms dual sided or are you mixing a single sided with dual sided memory? I ran the XP1800 on one old build until the next case saw an XP2600 there.

The 256mb dimm is a slower PC1800 memory forcing the clock down to the 100mhz fsb. The faster PC2100 won't backclock to the slower speed explaining why you heard the alarm since there was a conflict seen. With it now set to 133 you should be able to run both 512s without a problem unless one of the pair is bad.