Problems adding 4 GB DDR

[GeekyGirlfriend]

Boyfriend's computer acting up again... This time, he's trying to replace a single 512 MB stick with four 1 GB sticks (Kingston KVR 400, 2.6 v) on his Asus A8N-SLI motherboard with AMD Athlon 64 CPU. The computer won't boot with all four sticks installed. It boots ok with only three sticks, though.

I read some scary-sounding stuff on other forums - recommendations that involve removing the CMOS battery or raising the voltage of the memory and overclocking the CPU, etc. Before I do anything like that, I want to hear from you guys (I trust you not to steer me down the wrong path).

Is it possible one of the memory slots is bad? How can I find out? I tested each memory stick individually and the machine booted just fine with each of them, so I think the memory is ok. My own suspicions are either a bad slot on the motherboard or else I don't have the BIOS set right. The DRAM settings in the BIOS are set to AUTO with the "Over 4 GB Remapping" feature enabled.

Thanks in advance for any suggestions!

[mjc]

Will the computer get into the BIOS with all four installed?

[GeekyGirlfriend]

Hi MJC,

Thanks for your reply. No, the computer doesn't get that far with all four sticks installed. Ideas?

[mjc]

Removing the battery to reset the BIOS to defaults...

And possibly tweaking the RAM voltages.

But it is very possible that this board doesn't like this particular RAM all that much and nothing will get all four working.

[GeekyGirlfriend]

I like the way you think. <g> I know nothing about setting the voltages and wouldn't want to attempt it without help, and I'm sure if I remove the CMOS battery, I'll never get the thing working right again. It's doing just fine with three 1GB sticks for now, so I think I'll let sleeping dogs lie...

Thanks for your help!

[sifLord]

going by the kingston model number you posted, the ram sticks need to run at 2.6 volt (default ddr is 2.5 volt), there is no need to remove bios battery or overclock your cpu or even overclock your ram

give this a try if you are game ;-)

1/ put 1 or 2 modules in, boot to bios, alter the ram voltage to 2.6volts, (note: you do not need to adjust any other settings)

2/ save bios and exit

3/ shut down computer, resinstall the other sticks, reboot

increasing the voltage by 0.1volt is not overclocking those ram sticks because that is actually what voltage they are rated for, most ddr ram modules can be run at 2.8 volt

if the pc still will not boot, then reverse the procedure

Is it possible one of the memory slots is bad?

possibly, but i doubt that is the problem, basically you are not supplying the memory slots with the voltage they require to run effectively
i.e currently the ram is running "undervolted"

its a bit like trying to fill up 4 x 300ml cups of water (the ram sticks) but you only have a 1 litre jug to fill them(the voltage), so you are 200ml short in 1 cup

hope this helps

[GeekyGirlfriend]

Ok, before I have had a chance to try out your recommendations, the computer has stopped powering on altogether. Everything seemed to be working, then it just went dead. Hitting the power button causes the cpu fan to make maybe one revolution, and that's as far as it goes - no beeps, no lights, nothing.

I took all the ram out to see if it would power on, but that didn't cause any change. I tried reseating the ram; that didn't help either. The video card is firmly in its slot and has not been messed with.

Does it sound like this power problem has anything to do with the new ram? The machine worked just fine with three 1GB sticks for the past few days, but I don't know of anything else that could've caused this sudden power problem.

I'll try to figure out where the Power On contacts are so I can try shorting across them with a screwdriver. Thank you all for this forum and for your help!

[GeekyGirlfriend]

Here's an update... I downloaded Sylvander's flowcharts and started working my way through. Very quickly, the power supply became the prime suspect. So I'll have to fix that before I can get back to the ram problem. Back in the dark mists of time when I was a bona fide, toolbox-toting computer repair technician, power supplies were really bad about taking everything down with them - the mobo, vid card, etc. I don't know if the newer ATX psu's are like that, but maybe it's possible the power supply was at the root of Boyfriend's original problem with the ram.

Money's tight so it may be awhile, but I'll let you know how things stand once the power supply has been replaced. Thanks again for all the help!

[sifLord]

no worries, definately sounds like something is shorting or is getting inadequate supply of power, i would also check the mainboard capacitors for bulging/leaks as a precaution

[GeekyGirlfriend]

New power supply is installed. Whoopee! This is the first modular power supply I've ever actually messed with. The machine is booting up and behaving normally now that it's getting juice. So, back to the problem with the memory.

I set the voltage to 2.6. With all four sticks installed, the BIOS sees the memory correctly. However, WinXP gets past the splash screen ok and loads screenfuls of drivers, but bombs out when it tries to load EXPLORER.EXE, even in Safe Mode.

Since it goes past the BIOS and begins the process of loading Windows before it bombs out, am I correct in assuming it's a problem with Windows and not with the BIOS? Everything still works perfectly well with only 3 sticks installed. The problems only occur when all four sticks are in.

Thanks in advance for any suggestions.