I had 512 RAM physical mem.
Comprised of 256 sdram 133
My sys is a pent 111 with via 694x chipset 133 FSB clock
It has the capability for 1.8g ram roughly speaking
I installed the stick after I zero filled the HDD
Then I installed Win XP Pro >> all went well installed successfully it is the full version on one partition: C
After looking over the system info on the OS system it related only 512MB but I have 768 MB installed is there some other area that I must cover? Or is this amount of RAM recognized eg the no of 768??

So are you saying you had two sticks of 256MB each installed and then installed another 256 for a total of 768?

It should recognize the new Ram. I would be sure it is FULLY seated in it's slot. Sometimes, it appears it is, but the end clips aren't quite there. Remove the stick, reinstall it and turn the Computer on again..

Then, right click on "My computer"/Proprieties and see what the main screen shows...

If you have on board video, it would show less...But certainly not that much less!

You have three sticks of 256 MB, and the memory count only reports 512 instead of 768 MB, correct?

If the sticks aren't matched, that could be a problem.

1) You could try to switch the positions of the memory to see if that helps.

2) You could relax the memory settings in Bios slightly.

3) You could try the sticks one at a time to make sure they are all working.

4) You could test your memory modules with DocMem.

I had the same problem. My MB (ASUS P5A; Final Bios 1.007) would recognize only half of a 256MB stick. I tried to upgrade from 128MB (had two sticks of 64 MB, each stick having 8 chips on one side) to 512MB using two 256MB sticks (each stick had 8 chips on one side). Fired-up the computer and the Bios posts only 256MB total RAM.
Needless to say I tried to find out what was going on - looked everywhere, including this forum, and the ASUS tech site, the memory maufacturer site, read my MB manual for the 132th time - all to no avail. I finally went down to the local hyper-overpriced computer dealer here in Blacksburg and the chick from Taiwan told me I needed to use Double-Sided (16 chips on stick) PC133 sticks. She told me that it was a "common" problem...!! that 64MB and 128MB single-sided chips are usually recognized, but that the "the bigger", 256MB sticks had to be double-sided...seems that the (newer) single-sided 256MB sticks have higher density chips on them that are incompatible with older boards.
I've never seen this documented anywhere...but I bought the double-sided sticks from her and -voila!- they work fine (sold the others on E-Bay).
Oh well, "Such is Life", had a beer, shook my head, went to bed.
Peace, Brother

Yes quite correct what a maze of info I have learned just on the trial and error sim.
Nevertheless, I have another PC it is a relatively new chipset P111
acer 800 MHZ and so and behold it contains 3 banks the first 2 I have 256 133 sdram 10 ns all 3 banks are set for 10ns in my bios setup.
So the 256 ram that could not be recognized as my old p11 chipset is >> like you have stipulated an old board. I took the 256 which is identical to my p111 sys and plop it in the 3rd bank. It was not recognized, so I exchanged it with another 256 ram and again it was not recognized, I changed various ram around the different banks to no avail.
My question to you is >> is it hard to get the double sided 128 MB on each side?

I got mine at the local hyper-high priced computer shop...I'll Google the Net and see what I can come up with.

I wrote an email to this place and they replied that they stock PC133 double-sided (16 chip) memory sticks.

http://memorysuppliers.com/
Hope this helps.

Yes the site had all something to query is the speed or access time of the ns I have throughout my BIOS / inwhich I can change the various speeds for access/ But the times showing for all my 3 banks is 10ns
I can change to 8 or, but I wonder if the related speed of the desired memory that I notice on the site is 7.0 ns ? Nevertheless I will try if not successful then i send back again thanks for the site/