7200 damage from EDO RAM?

[jdlanza]

I have read (too late) in several places that EDO RAM can damage the motherboard of a 7200.  What I can't find is any information on what is the damage that gets done!  I made the mistake of loading my 7200 with EDO RAM chips, and now I get the breaking glass sound whenever I try to start up.  What gets damaged on the motherboard and is it recoverable?

Thanks in advance! 

 

[Byrd]

It’s news to me that using 5V EDO RAM can “damage” a system requiring 3.3V EDO modules; I’d pull the power

cable, PRAM and leave it be for 24 hours before cleaning and installing the correct modules back in.

 

[jeremywork]

7200 requires 5v memory just like most others of the time (3.3v and 5v modules are keyed differently and should never fit the incorrect slot.)

The issue here is EDO vs FPM, and Apple did officially state this incompatibility, though unfortunately there's not much technical info on what goes wrong...

https://www.macgurus.com/products/motherboards/mbppc7200.php

https://web.archive.org/web/20070812065510/http://docs.info.apple.com/article.html?artnum=20101
 

 

[jdlanza]

The issue here is EDO vs FPM, and Apple did officially state this incompatibility, though unfortunately there's not much technical info on what goes wrong...
 

Exactly, @jeremywork!  And Google also turns up little.  The Apple tech note on this issue is no longer available from the usual sources.  Oddly, what find indicates the 7100 would happily use EDO, so perhaps the memory controller in the 7200 is different and doesn’t like EDO?

 

[jeremywork]

The second link in my post is the Apple tech note, but it's not really any help other than to show Apple disclosed this officially.

I'll defer to the wisdom of those who know the Catalyst platform better, but if I recall correctly the 7200 was an entry level version of the 7500, both of which are significantly different from the 7100, which was before the PCI "PowerSurge" redesign. Other notes also point out it used a 64-bit data path rather than 128-bit and therefore didn't support interleaving, which all other PowerSurge machines did. I suspect the memory controller was created as a budget option and either overlooked EDO or they didn't want to spend extra time to test/fix it. (Other PowerSurge models will treat EDO as normal FPM anyways, so maybe it was deprioritized.)