BX chipset functions

[Toaster]

Hi folks,
I was "exploring" the BX chipset by "tripping" certain registers to enable them and disable them. I found something that wasn`t documented as far as I can tell. What I found was a memory "interleaving" feature. This feature splits the memory clock and reduces memory access times. So far, I haven`t seen any BIOS`s that allow manipluation of these chipset features but they may exist. These features are automatically disabled unless the following is true:
1. The installed memory modules are an exact match of 64MB modules or greater upto the maximum size supported by the chipset/system board maker.
(this match is defined by the eprom used on all SDRAM modules)
2. The modules are of the PC100 type with an access time of 8ns or faster but may not include PC133 memory. (in my case PC133 memory worked well)
3. The memory modules are installed in pairs with no other mismatched memory installed or an odd number of modules installed. (pairs only of matched modules)
4. The BIOS "memory latency" options are set to "automatic".
(if you define CAS/RAS latency, the feature disables itself)



This was on an ASUS P2B-F system board with 4-64MB modules of exact modules installed. When the system board detected "alike" pairs, memory access performance increased by about 30%!. This was a noticable speed increase which also resulted in increased frame rates in 3D video intensive apps. Since the intel BX chipset is licensed to other chipset vendors/designers (VIA and others) this may work in those systems as well. This resulted in a substantial speed increase without overclocking. If one defines CAS/RAS memory timings in BIOS with "interleaving" enabled, system performance actually *DECLINES*. Be aware that this seems to work with systems that have DIMM sockets in multiples of *2*. I tried this with a P2-B system board that has 3 DIMM sockets and the feature would not enable. I`m researching this as we speak and soon may have useful data before long regarding this. I also found other chipset functions and as they come to bare i`ll keep you folks informed.

The bottom line is this, buy your memory in pairs and install ONLY pairs for a speed-up thats noticable.