CPU:RAM Ratio

[Goatie]

Hey,

I recently made a post about a computer I'm building for a friend and the members of this board helped me out (thanks). Anyway, I now have another couple of questions, this time dealing with overclocking.

System specs

A64 2800 +
Epox nforce 3 -250 MOBO
512 MB PC3200 Kingston value ram
etc.

Before my questions I want to go over my understanding of CPU/RAM ratios for A64s(If you want you can skip to the questions). Because of the on-die memory controller the performance hit from not running your ram in sync with your fsb is minimal. Because of this, people with not so great ram often decide to run async so the processor overclock isn't held back by bad RAM. My 'FSB' maxes out at 285(default V) on my mobo, my ram however is only stable at 217 (2.8V).

Questions:

1) How do I change the CPU/RAM ratio. I do not see any option for this in the bios. The closest I've seen is an option called "MAX MEMCLOCK" with the variables - Auto, 100, 133, 166, 200. The manual states that setting this option to 200 will stop the ram from going above 200mhz. However I tried setting this to 200 and when I change the 'FSB' the ram still trys to run in sync. If I could lock the ram at 200 that would make me a happy camper (what a dumb expression).

2) Ideally, I'd like to run my ram at 217 and my processor at 171. Is this possible? If so, how?

I have tried doing some research and couldn't find the answers to my questions, however if someone has a link they think is relevant, I'd be more than happy to check it out. Thanks again.

 

[Lithan]

You can't underclock your processor via the bus. I'll assume you meant 217 on ram and 271 on cpu. 9*271=2439 2439/11=221.

With the 166 setting you'll get 271 CPU and 221 ram. .

 

[Concillian]

Yep, you have to choose between 221 MHz (for a 166 setting, which will give a 5:6 ratio) or 174 MHz (for a 133 setting, which will give a 2:3 ratio)

I SO wish they'd just let you set the integer divider for CPU speed, then you'd be able to set it to 12 and get 203 MHz RAM speed, but NO you have to set some ratio that doesn't even really mean anything, because it often doesn't run at the ratio speed because of the whole integer divider thing. Seems like a lot of confusion for no real reason.

Eventually a mobo maker will wake up and do things this way. Until then, you're stuck with pretty limited options if you don't have a DFI LANParty.