I have a pentium 2.4 CPU running with an FSB of 533. I also have DDR400 ram (1024MB, in 2x512MB DIMMS). I bought the RAM and started having problems with my motherboard, model MSI 84E Max as it only supports RAM up to PC2100. (For information: Problem, when PC is booted up from cold up I get a message stating it can't boot from the floppy drive (No bootable Media). I then control-alt-delete to restart it and it boots up fine (something funny going on). Therefore I am looking to upgrade my motherboard to the ASUS P4P800 Delux, which supports DDR400 RAM. I was about to purchase the board when I noticed on a review the fact that DDR400 is only supported on this (and other i865PE/Springdale boards if the FSB on the CPU is 800Mhz. Will the RAM just run at the lower speed of PC2700 (333Mhs) on these boards or am I likely to encounter problems? I could live with the lower RAM speed as I paid little more to go up from PC2700 to PC3200 RAM and can just utilise the RAM at its full speed when I upgrade the CPU in a years+ time. I'd rather avoid problems with buying a new board and ending up at square one. Also I haveread reviews where the CPU/RAM etc are overclocked, whith this configuration what can I do (Reviews I have seen have been for MB FSB 800 and CPU FSB800) Thanks in advance for any help.

Before scrapping the mobo & buying another...try reading up on what you need to do to get this one to run correctly. From what I can tell, your board is particular about RAM settings, so it's possible a BIOS tweak is all that's needed... This was taken from the MSI website: "Due to the High Performance Memory design, motherboards or system configurations may or may not operate smoothly at the JEDEC (Joint Electron Device Engineering Council) standard settings (BIOS Default on the motherboard) such as DDR voltage, memory speeds and memory timing. Please confirm and adjust your memory setting in the BIOS accordingly for better system stability. Example: Kingston HyperX DDR500 PC4000 operates at 2.65V, 3-4-4-8, CL=3. For more information about specification of high performance memory modules, please check with your Memory Manufactures for more details." http://www.msicomputer.com/product/detail_spec/product_detail.asp?model=845E_Max

It officially supports DDR400 but it unofficially supports all the way up to DDR700 or something, just double what your FSB goes up to in the BIOS and that will give you the theoretical max ram speed for your board. Says somewhere in my 8knxp manual.

Oh yeah if you get a p4p800 and you have ddr333 it will boot at 333, if you have ddr400 it will boot at ddr333 not ddr400. Cause the 865 and 875 chipsets only support ddr333 with the 533mhz FSB cpu's, so if you got ddr433 it would boot at 333, then when you overclock it to 160FSB the ram will just be getting to ddr400. So if you want to overclock you'll need ddr433 if you want to go much further than 160FSB, cause when you turn the fsb up the ram speed goes up and your ddr400 won't be able to handle much more than 420-433..more if your REALLY lucky.

First of all, I doubt your PC3200 is the problem with "can't boot from floppy drive" error message. If don't overclock your MSI 845, the memory default to 266. PC3200 is backward compatible. If you do overclock (mine went 3.12Ghz using the same board, replaced since) your memory should work fine. Secondly, if you overclock the CPU with the P4P800 and overclock your memory from 266 to 333, you may end up over 400 which might not work as others had mentioned the sensitivity of memory setting /matching in all 800mhz boards. For reference, I am running Corsair PC2700 to 384mhz with a board that supports to 333mhz only. Finally, you better have name brand memory using 800mhz boards.