PC2700/3200 backward compatible w/PC2100 RAM?

[wpcoe]

I need a refresher in RAM history. An old Athlon motherboard's (VIA Apollo KM266) specs call for "184-pin DDR DIMM, up to 2GB DDR200/266 (PC2100)."

Would PC2700 (DDR 333) and/or PC3200 (DDR 400) RAM be backward compatible and work in that mobo?

 

[Deders]

Yes they should be, the will have Jedec profiles for 266 that the motherboard should automatically choose.

 

[Compman55]

Yes it will work fine, however back in the day I remenber the bios often did not auto configure the ram settings correctly. You will want to go in and double check before loading the OS. If the settings are off, the memory can give errors. Manual adjustment usually fixes this.

 

[wpcoe]

Thanks for that reassurance.

On DDR RAM, was there any compatibility problems if the DIMMs were double-sided? (i.e. If there are RAM chips populating both sides, did that matter on some motherboards?)

I recall getting some RAM (years ago) that at the time I thought would work but didn't. It got very hot (to the point of smelling hot) and I had to return it. I can't recall why it was incompatible. Right now the computer has 3 x 256MB DIMMs and I think the DIMM I returned was a 1GB stick. Any DDR RAM I find now are 1GB double-sided DIMMS.

From my notes, the mobo has a VIA Apollo KM266 chipset, and I haven't found any specs online for that.

Are the odds in my favor of picking up one (or two) of 1GB double-sided DIMMs and having it be compatible?

 

[ICCUSA1]

In general motherboards should fit any memory rank to give DIMM manufacturers flexibility in their chip density. I do believe there are exceptions but they tend to be very rare. That chipset is pretty old so there isn't much detailed technical documentation floating around. I would say that you should be good with compatibility with double-sided DIMMs.

Your experience with the RAM from a several years ago that was running too hot... just from that it doesn't really sound like it would have been an incompatibility issue. Sound more like there was a faulty component such as a heatsink, or perhaps there was a limit on a maximum memory per row. I have heard of maybe 1 or 2 occasions where installing RAM that exceeded the amount that the motherboard can address per slot caused overheating problems. But that's not typical either. Usually it will just prevent you from using the full slot capacity.

Good luck!

 

[wpcoe]

Thanks. This is for my 96-year old mother's computer. The old clunker is all she really needs, but it -- as you might imagine -- is rather slow with that CPU and only 768MB RAM. I'd like to have at least 1.5GB in there, even though she's only using IE and Thunderbird on WinXP. I'm going for a visit later this week and plan to stop by Fry's near the LAX airport and see if they actually have the 1GB DIMMs in stock. Web site says they do.