A computer components & hardware forum. HardwareBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » HardwareBanter forum » General Hardware & Peripherals » General
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

PC 4GB RAM limit



 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #1  
Old May 13th 05, 10:13 AM
Tim Anderson
external usenet poster
 
Posts: n/a
Default PC 4GB RAM limit

The cheaper motherboards (ie. most of them) for P4 or Athlon 64 support a
maximum of 4GB RAM, even if the motherboards and processors support the
AMD64 extensions that can address sqillions of GB. On the other hand, more
upmarket boards support more RAM - up to 24GB or maybe more - for Xeon and
Opteron.

If you buy one of these 4GB boards and install 4GB RAM, you don't get the
use of all of it. The top of the 4GB address space gets shadowed by system
functions such as PCI Express addressing. This is not just a small detail
- typically you lose 1GB of your 4GB. See:

http://www.itwriting.com/blog/?postid=152

I can't at the moment find a clear explanation of this. I understand about
the shadowing, but the question of course is why a modern board can't use
a higher range of addresses to make the full 4GB available to the OS. The
manufacturers mutter about "PC Architecture", but then again they also
make boards that *do* overcome this limit.

With PAE, PC processors have been able to address more than 4GB for years.
So why are we still running into this limit?

Tim


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
overcoming the 300 gigabyte limit || Homebuilt PC's 2 February 2nd 05 04:30 AM
Controller that allows drives over 137gb limit?? John Barrington General 4 June 22nd 04 11:10 AM
Somewhat off-topic...Customizing the TIF limit for Internet Explorer MovieFan3093 Dell Computers 2 October 23rd 03 03:22 AM
Temporary Internet Files limit HistoryFan Dell Computers 3 October 16th 03 03:32 PM
Limit to processor speed? ZITBoy Homebuilt PC's 31 September 17th 03 12:46 AM


All times are GMT +1. The time now is 08:30 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 HardwareBanter.
The comments are property of their posters.