Hi there, I just bought a new computer with Vista Business x64. I am moderately good with computers and have spent a large number of hours researching to resolve these problems with no luck so far....in fact I struggle to find people with the same problems as me.

My system spec is this:
Asus P5E (x38 chipset, latest bios)
Intel Core 2 Quad 6600 (OC @ 3600, water cooled)
4GB (4x1) 800mhz DDR2 G.Skill F2-6400CL4-1GBHK
2x 512mb HD 3850 in crossfire (kind of)
2x 250GB Hard drives in RAID 0
Windows Vista Business 64-bit SP1

The main problem is the RAM , this came with 2gb (2x1) DD2 800 RAM to begin with; this was usable by all means but I decided to upgrade as I use RAM heavy applications and games often. So I bought the same identical RAM again now giving 4gb (4x1) RAM.

I have read many people complaining about seeing 3GB of RAM on 32-bit but that is not my problem as I am 64-bit....I’ve even read about people having problems with the 4th memory bank (nvidia chipsets I believe) but that is also think this is not my problem, or even windows not booting but mine is fine. So far I have not seen anyone else post about the same problem as me.

My problem is that although my Windows sees 4GB’s of RAM and MOST of the hardware detecting programs see 4GB (Everest, PC Wizard, CPU-Z, Steam, 3DMark06 etc etc) Windows only seems to use 2GB’s. When I added the new 2 sticks of RAM everything seemed fine, my computer booted up normally and windows recognized the RAM straight away (which is should on x64) but over the next few days I noticed the computer only seemed to use 2GB’s and I saw no performance increase by having 4GB’s, in fact sometimes when using RAM heavy applications I would suffer with very bad “computer lag” which should not happen with this PC.

This is some of my RAM system information:

Installed Physical Memory (RAM) 4.00 GB
Total Physical Memory 2.00 GB
Available Physical Memory 789 MB
Total Virtual Memory 4.24 GB
Available Virtual Memory 1.95 GB
Page File Space 2.29 GB
Page File C:\pagefile.sys

My task manager performance tab says i have 2046MB (should be 4092) usually between 700-1000 cached and less than 50mb free. Basically my system while idle takes around 50% of the RAM (1gb), and while using RAM heavy applications or Games can take up to 90% which cause a lot of lag.

At first thought that 2gb are used for windows services and 2gb for app's etc, but i cannot find any evidence for this i just see my RAM half full before i open anything and getting fuller as i open more apps. it just seems as 2GB of the 4GB are not being used.

I have checked that the memory remapping is enabled in BIOS which it is, I have tried manually installed the KB929777 hotfix but it says “The Update Does Not Apply To Your System” even though It is not already installed. I moved the RAM around once too I have probably tried most things, but please if anyone knows of any way to fix this I would much appreciate it; even if I have already tried your method go ahead and say it anyway.

If you have any questions that about something I have missed feel free.

Unfortunately I cannot really say what setting I have played around with in Windows or BIOS but probably quite a few and also have a fair few programs installed.....but I cannot think of anything that would cause this.

I also have 2 unrelated issues that I would like resolving but for now lets just stick with the RAM.

I finally found the solution after a number of hours searching and testing.

Going to Start > type MSCONFIG and press enter > go to BOOT > Then Advanced Options > Make sure that Maximum Memory isn't
checked. If it is, uncheck it and reboot.

Very simple, but no one mentioned this elsewhere.