AMD64 MoBo and RAM

[maverick77_uk]

Hi all,

I've built a few computers in my time, but I'm looking into buildng my first AMD64 comp. Got a quick question.

When the MoBo supports standard DDR RAM (2100, 2700 or 3200), traditionally, the speed of RAM required was the system Bus speed, ie a system buss of 166 needed 2700 RAM. However, as the AMD64 no longer has a system clock in the true sense of the word, just this hyper-transport or whatever, at 2000MHz, how do you not fry your RAM, if you put say 2100 in? Do you now specifically tell it in BIOS that it has 2100 RAM so only communicate with it at 133 MHz? Do you therefore get the choice of what speed RAM to stick in?

Cheers!

Steve

 

[lynx6200]

I cant answer that in the technical sense, but I think I know what your saying, sorry If i got it worng. Anyway, the bus speed will only support that type/set speed of ram. So, in other words if it supports 2100, it will run up to that speed, but if you put a higher amount like 2700, it shouldnt hurt it, but it will still only run at 2100.

 

[Hairy_Lee]

the hypertransport is an internal bus that connects to items such as the agp or pci buses. athlon64 CPUs have their own memory controller, which runs at the speed of the clock generator. this is also where the hypertransport gets its speed derived from. The hypertransport isn't there solely for ram but other components too. hope this helps

 

[Praetor]

when the mobo supports standard ddr ram (2100, 2700 or 3200), traditionally, the speed of ram required was the system bus speed, ie a system buss of 166 needed 2700 ram. however, as the AMD64 no longer has a system clock in the true sense of the word, just this hyper-transport or whatever, at 2000mhz, how do you not fry your ram, if you put say 2100 in ? do you now specifically tell it in bios that it has 2100 ram so only communicate with it at 133 mhz ? do you therefore get the choice of what speed ram to stick in

.
"Traditionally" there was no "need" relationship betwen the core-clock and the type of memory clock (i.e., a 166FSB machine would still boot with only 133MHz memory). Granted its ideal to have 166MHz (or even faster) memory in place but certainly not critical

With the A64 way of things, assuming again you want to run 1:1, you need to (a) set 1:1 in the BIOS (usually its an entry like 2:1) and (b) Consider this:

1. net clock = core clock x multiplier
2. Assuming 1:1 then we know divider = multiplier
3. memory clock = net clock / divider

the hypertransport is an internal bus that connects to items such as the agp or pci buses.

That definition also applies to FSBs The distinction between the two is that HTs are bidirectional/full-duplex and FSBs are not