Weird problem when adding a new 128MB DDR stick, can sum1 explain what's going on?

[be2kz]

Hi, below is my computer specification:

ATHLON XP 1600+
K7S5A
DDR 128 Samsung Chip (Old)
DDR 128 Infineon Chip (New)
GF2 MX400 32MB
Quantum Fireball 15lct
Asus 52x (Pri Master) + Teac 32 (Sec Master)
350watt PSU

Using CheepoBios version 1129
Memory set at Ultra 2-6-2T (works really stable)
Clock set at 133/133 (no overclocking)

I experienced a very wierd problem yesterday. Recently, I bought a new DDR stick (which is the DDR with the Infenion chip). I placed the new DDR stick at bank 1 (the farther slot from CPU). I turn on my PC, everything work well, POST detects 262144KB. I restart my computer, then problem occurs, POST detects 131072KB only at bank 1). I thought my DDR slot was dirty, so I turn off my computer, cleaning the bank 0 slot, and turn it on again, POST says 262144KB, then I re-boot again, like before, POST only detects 131072KB. I tried this several times. Problem occur at 2nd,4th,... boot. 1st,3rd,5th... is normal. Then I remove the new DDR stick from bank 1, everything work back to normal, POST detects 131072KB at bank 0, even if I turn on or re-boot my computer, everything is normal. So I conclude my bank 0 slot and my old DDR stick is good. I placed the new DDR back to bank 1, and the problem appears again.

The same when I turn on my computer, POST detects 262144KB, I press del to enter BIOS menu, when BIOS menu appears, I reset my computer, POST detects 131072KB, I press del again, then I reset, POST detects back to 262144KB, I press del, then reset, POST detects 131072 and so on.... back and forth from 262144KB to 131072KB.

Then I switch the new DDR stick to bank 0, and the old one to bank 1. The problem dissapear. Even if I turn-on or re-boot, POST always detects 262144KB memory avaiable on my system.

So, what's going on here? Is this a BIOS bug? Or maybe even a motherboard bug? Can someone tell me what's going on? I really really courious about this.

Thanks for your answers...

[lostinms]

Ok I had a simular(sp?)problem but with a stick of pc133 memory. I upgraded my puter with a stick of 512m ddr 2100 and I took my 2 256meg pc133 and put one in my wifes puter which has a K6-3 in it and the other in my moms puter which has the same motherboard as mine.

Well when I tried one stick in my wifes puter and booted it up it said I had more memory than what was in there. I already had a stick of 128meg pc133 in the first slot. I put one stick of the 256 in the second slot that is when it posted more memory than I had. So I tried the 3rd slot on my wifes puter and it would not even reconinzed the memory stick. Well the other stick of 256 work great in my wife computer so I got my mom and tried to see if the bad stick would work in here puter seeing it is a newer puter.

Well it would not work in the second slot but when I put it in the first slot it worked like a charm so I think it is the memory more than the motherboard or a Bios bug.

[twistedjheff]

As I see you are using two different brands of DDR memory modules and sometimes problems arise when your using two different brands of memory modules my suggestion is go get a 512 meg ddr or if not get a ddr module of the same brand and also get a non-ECC memory module cause the sis chipset doesnt want this kind of memory module for some reason! i hope this helps!! God speed