RAM upgrade problem

[Stalker]

hey guys, i hv an intel 845D AGP chipset on my comp. it has two slots for SD-RAM

now, here's the problem
i have 2 128 mb 133Mhz modules. i hv got my friends 256 mb 100Mhz module 4 some days. but when i try to put the 256 + 128 combination, the system detects it as 256 mb or sometimes refuses to boot up. i tried this with the other 128 module as well. 4 some reason the system does not detect the total RAM as 384. is this a memory timing mismatch??

Also where can i find out the maximum RAM capacity supported by my mobo??
will upgrading my BIOS help??

[satyamy]

theri is one utility called Everest from
http://www.lavalys.com or www.download.com
This will tell you your Motherboards RAM Capability

[Stalker]

i had checked it using @BIOS agent and it had said tat the max capacity was 512 mb.......................will try everest

[d]

yea the clock speeds have to match i think.. else some mobos have an order of slots to put in diff speeds.. as in fastest in slot 0, next in slot 1 .. like that.. perhaps you cld check that out in the manual..

[Stalker]

got everest...........ran report wizard says

Memory Controller Properties:
Error Detection Method 8-bit Parity
Error Correction None
Supported Memory Interleave 1-Way
Current Memory Interleave 1-Way
Supported Memory Speeds 70ns, 60ns
Supported Memory Types ECC, SDRAM
Supported Memory Voltages 3.3V
Maximum Memory Module Size 4096 MB
Memory Slots 2

does it mean that i have 4 GB RAM capacity?? wat is ecc ram??
this hasn't helped by problem. plz advice...

[vandit]

ya the clock speeds have to match