T21 RAM issues?

[LegendaryKA8]

Hey there. I've just encountered a strange problem with upgrading my RAM in my 2147 T21. I recently purchased two 256MB sticks of PC133, which I'm pretty sure is the right type to be using in this machine. I currently have two 128MB sticks in here. Here's the combinations I tried and the results:

Both 256MB sticks: Powers on, won't go to splash screen.

256MB stick in main slot, 128MB in secondary: Same situation as above.

128MB in main slot, 256MB in secondary: Boots to splash screen; BIOS recognizes 384MB RAM. Attempts to boot into Win2K; once the Win2K loading bar completes, it spontaneously reboots, ad infinitum.

128MB in main slot(and both slots): Turns on, splash screens, and boots as per normal.

I'm scratching my head on this one. The only potential solution I can figure out is that this mobo can only use PC100 RAM, and the 133 won't downclock for some reason. Any suggestions?

[RealBlackStuff]

I'm afraid you bought the wrong RAM.
T20/21/22 only take PC100 RAM, the PC133 is meant for a T23.

[nikki605]

When I upgraded my T21, I found out it would only take "low density" PC100. There is a sticky topic at the top of the T2x & T3x index page that talks about it. Also, if you search the T2x & T3x forum for the term low density you will find several discussions on memory modules.

[rkawakami]

To clarify what RBS and nikki605 said earlier, it is possible to use PC133 memory modules in a T21 but it must be of the "low density" type. To easily identify those modules, simply count the number of memory chips that are in both sides and use these rules:

256MB module
- 16 chips is low density and will work in a T2x system
- 8 chips is high density and will not work in a T20-T22

128MB module
- 8 chips is low density and will work in a T2x system
- 4 chips is high density and will not work in a T20-T22

There are some rare cases where a low density PC133 module will not work in a PC100 system but this is usually due to a mis-programming of the SPD (Serial Presence Detect) memory on the module.

[LegendaryKA8]

Sorry about the wait. Good information all abound; thanks once again. Looks like I got my hands on the wrong RAM.

I had one more quick question... will high-density PC100 work in the T21, or does it still need to be low-density?

[rkawakami]

High density will not work in any T20, T21 or T22 system. T23 is the only T2x system which can use high density modules. Doesn't matter if the module is speed rated as PC100 or PC133. The main problem is that the refresh characteristics are different between the "low" and "high" density memories.