asus p2b266 question

[mikeward]

I'm considering the asus p4b266 mobo, which can have a fsb running up to 200 MHZ. Will I be able to set the fsb on that board higher to accomadate the newer procs and RAM later in the year? Like DDR333 RAM and a p4 that uses a quad-533 mhz fsb? Or is the RAM speed set for DDR266/DDR200?

And, if anyone knows of any good websites that explains how fsb relates to RAM speed and how you can have DDR266 running on a board with a quad-400 fsb but not DDR333, I'd love to go read it...

 

[mbf]

I'm not sure if I can give you the solid technical info, but let's try a bit anyway. The ASUS P4B266 uses the i845D chipset and most of your issues are chipset related, so in this case they should hold true for all i845(D) based boards.

The i845D supports an FSB of 100MHz, and since it is capable of relaying 4 words on the bus for each clock cycle, it's refered to as quad pumped. The FSB is (as far as I know) only relevant for the processor speed and since the i845D only supports 100MHz, all speeds above this (133MHz for 533MHz quad pumped) require overclocking of the i845D, which may or may not work.

The i845D supports DDR memory clocked at 100MHz or 133MHz, which because of the dual data rate (DDR in DDR RAM) is also refered to as 200MHz or 266MHz. Dual data rate could just as easily be called double pumped. It means the same thing.

In the "old" days all (bus) speeds were derived from a single "main" value, often the FSB, eg. when the FSB would be clocked at 100MHz the AGP port would be clocked at 2/3 or 66MHz, the PCI bus would be clock at 1/3 or 33MHz and 133MHz RAM would be clocked at 1.3/3. Every increase to the FSB would automatically also overclock all buses locked to the FSB, which could lead to disastrous results.

Many boards today (both Intel and AMD based) allow for asynchronous clocking, which means that you could overclock the FSB, but the PCI bus and AGP port would stay locked at their correct speed. Still, in any case you would be running the system out of spec, which may or may not work. No guarantees can be given. Your system may even (seem to) work, but will break down sooner than would normally be the case. But that's all hypothetical...

What that means is, no, the P4B266 will not (officially) support P4 processors using the 533MHz quad pumped bus. You should however be able to use DDR333 RAM. It just won't do you any good. If anything it will run as fast as DDR266 could possibly go. You should note however, that there really isn't any official DDR333 standard, which means that the JEDEC organisation hasn't approved of the DDR333 spec. All DDR333 hardware (boards, chipsets memory) is more or less how that particular manufacturer interprets what DDR333 should be.

Hope I could help you some and not just confuse you even more...