Question: I have installed total 4GB memory on my motherboard. However, it can only recognize around 3GB or less. How should I do to recognize 4GB totally?(2/17/2006)
Answer

lease refer the description Q4 of Q&A-20.
http://www.asrock.com/support/QA/TSDQA-20.pdf
This limitation applies to most chipsets & Windows XP 32-bit version operating system.
If you want to get 4GB memory for your system, below two conditions must be required:
1. The memory controller which supports memory hole(memory remap) functionality is used. The latest chipsets like Intel new chipset, or other chipsets and AMD K8 CPU architecture can support the memory hole(memory remap) function.
2. Windows XP Pro X64 Ed. (64-bit) or other OS which can address more than 4GB memory.
http://www.intel.com/support/motherboards/server/sb/cs-016594.htm
http://www.asrock.com/support/faq.asp?Model=General
I got both conditions,
Memory Hole is ON/ENABLED and I am using Windows XP Pro X64 Ed OS!
It may show I'm using 3.5 gigs ram, its still good enough for me.
I got SpeedFan and FreeRAM XP Pro. And Memtest from this link:
http://www.hcidesign.com/memtest/
SpeedFan
No problems, a minor raise and lower 0.05 power.
FreeRAM XP Pro
Using 85% of free ram (3.5 Gigs), still better than nothing.
Memtest
Checked and tested 900x2 (1,800), 1,000x2 (2,000) and 2,000x2 (4,000) MB. Over 200% and 2 1/2 hours,
No errors!