I had Windows Vista Installed earlier (Ultimate with sp1). It showed me as having 4 gigs of ram. Before I installed Service pack 1, I had 3.5 or 3.25 gigs visible.
 
Now before I installed Sp1 I had only 2.5....What is going on? With SP 1 it sees 4 gigs...but why is it that I only have 2.5 gigs usable compared to before which was 3.5 or 3.25??? This is nuts
 
If any1 has an answer plz let me know
 
Thnx

Did you change out any hardware?

Ha Ha Ha Ha Ha Ha Ha MS made Vista SP1 report RAM above 3GB properly.
But you still run into the 32bit ram wall.

It is a Display Change ONLY
 
 
You do not and will not gain more RAM access than you had before.  If you need that that much RAM in a windows environment you will have to go to a 64 bit OS.

Like bobbknight said, but the official answer...
 
http://support.microsoft.com/default.aspx/kb/946003
 
Clint

Exactly, if you run a 32 bit OS, you can't take advantage of all 4 gigs, the OS gets messed up on the addressing.  Someone correct me if I'm wrong, but MS may let you upgrade to the 64 bit pretty cheap since you already have the 32 bit OS.  Anyone else heard that?  Anyway, if you could do that, it should let you use all 4 gb.

If you have the 32 bit retail version, MSFT will send you a CD of the 64 bit for something like $11 for shipping and handling.    If you have a store bought computer, which has an OEM install obviously, or bought an OEM copy of the OS, then you have to buy it.

Yes I understand that lol ...I kno I can't use 4 gigs of ram, but I had 3.25 displayed before and now only about 2.5 (even though Vista SHows the 4 gigs)
 
Since the change I have 5.7 Vista Experience compared to 5.9 when Vista saw 3.25

You guys aren't reading his question.  He's asking why it used to show 3.5gb (pre-sp1) then he reinstalled the OS and it shows 2.5gb (again, pre-sp1).
 

Thank You thats exactly what I'm asking

VGA: 2x's 9600 GT 512 SLI    
 
I pulled that from your signature.  That right there means that no more than 3GB can be addressed.  and you would have seen a drop of about half a gig by adding a second video card, you do that recently?

well I changed these video cards from 2 other 8800 GTS 320.  
 
Whats funny is that I didn't re- install windows when I changed the Video cards. So it still showed 3.5 or 3.25 I can't remember.
 
So will it affect my system performance? or what becaues it did affect my 3Dmark results a little bit and my Windows Experience.

Also I just read that your page file counts toward the total available but I disagree with that.  You may want to research that part.

have tryed booting up with just 2 gig and see if it says 2 gb and then shut down windows and add other two gig of ram.also is this your ram:2 gig . http://www.newegg.com/Product/Prod [...] 6820227198 and also these 2 gig ram http://www.newegg.com/Product/Prod [...] 6820227124

I have 4 gig of g-skill 800 and xp shows 3.5 which is correct.

Scotteq
If you have the 32 bit retail version, MSFT will send you a CD of the 64 bit for something like $11 for shipping and handling. If you have a store bought computer, which has an OEM install obviously, or bought an OEM copy of the OS, then you have to buy it.

is correct.and it would be worth doing also.hope this helps you  
 
also have two pc at my shop that we just loaded vista sp1 and both show 4 gig of ram.it will show it correctly!
 
may be time for old major to upgrade to vista now uh.

Well with Sp1 from vista it shows 4 gigs....but only 2.5 usuable compared to 3.5 usable from before.