Do all socket 775 and AM2 motherboards support EM64T?

[Fuzzy33]

Hi:

According to Trusted Reviews at http://www.trustedreviews.com/article.aspx?page=8232&head=0 the Dell-customized motherboard that comes with a top-of-the line Dell XPS 700 with a 64 bit Core 2 Duo chip does not support EM64T extensions, also known as Intel64. Accordingly, these computers cannot use 4 gigs or more of RAM, even though Dell offers this as a US$300 upgrade option. I assume that this is true for all Dell home and small office computers (though perhaps it only applies to Intel chips, not AMD chips).

This seems like a major Gotcha!, since I thought that support for extra RAM was the main reason for 64 bit CPU chips.

I would think that it would be an important criterion for selecting a motherboard, but I don't think that I've seen this highlighted in motherboard reviews. Is that because it is a non-issue since everybody else supports EM64T? or nobody does? or it doesn't matter?

So that's my question. Is it unusual for motherboards that support 64 bit chips to not support EM64T memory, and accordingly to be limited to about 3 gigs of RAM even when 64 bit Windows is installed? What about Compag and HP pre-built computers? What about motherboards for build-it-yourself computers?

Fuzzy

 

[Aluvus]

Dell may have disabled it in BIOS, though it would be a bit odd. Even odder, Dell specifically notes that 64-bit Windows XP is required for 4 GB of memory, and does not offer that as an OS option.

I am not aware of any other motherboards with EM64T specifically disabled, though that does not prove they don't exist. This appears to be a Dell-specific nerf, although it is possible other OEMs do something similar.