FSB and Dram Freq. I'm feeling dumb here, help me out.

K

Kranium

Limp Gawd
Joined
May 27, 2011
Messages
432
Man I remember when Ram was simple, now I have to double the data rate, then double it again in dual channel mode? My brain hurts now :(

So I am just playing around with my "new" setup consisting of a Presler 955 processor in an Asus P5k board. Memory is Kingston PC8500 DDR2.

So like a good boy I read the manual and it says "If you install a DDR2-1066 memory module whose SPD is ddr2-800, make sure that you set the DRAM Freq. item in BIOS to [DDR2-1066MHz]." Well I took that to mean whose SPD is AT LEAST DDR2-800. So I set DRAM Freq. to 1066 and the FSB Freq to 266.

This nets as a 1:2 multiplier according to cpu-z. In this setting I could only up the FSB to 275 and POST. This results in a Dual Channel speed of 1100MHz.

Now I'm reading some stuff and realize that I need to set the DRAM Freq to 533Mhz and I do that. Now I have the FSB at 300 thus a "effective" FSB of 1200MHz. This was just my first boot, and I'm assuming it's MUCH more stable as I have been on here a few Hr now.

My questions;

1) Why doesn't Asus just list "DRAM Freq." as what I guess it really is, which is DRAM to FSB ratio...kind-of.

2) What was I effectively doing at the 1066 Freq setting that limited the OC so much? (A math equation would be greatly appreciated)

As I see it now I had 275X2... DDR....X2 again.... dual channel....X2 AGAIN? DRAM [email protected] FSB Ratio = 1100 ??

.....and if so, how is this version different than 275X2 X2 X1(DRAM Freq@533) X1:1 Ratio = 1100 ?


Any insight would be great! I just want to know more for future OC adventures!
 
Yeah read that a while ago, not much on memory settings. I don't feel so bad now though as it seems no one else knows what's up with this stuff either. :-P
 
Dual channel does not have anything to do with the settings. When you had the fsb set to 300 what was the dram frequency on cpu-z memory section, also fsb:dram ratio and cpu multiplierbeing used.
 
When FSB in bios is set to 300, like I said that is a 1:1 DRAM 300MHz multiplier 14x

My question centers aroud the setting labled "DRAM Frequency".

Not MY scrren shot FYI.

dividerslistatstock.jpg


The manual made it look like I needed to set that at DDR2-1066.... but that makes the FSB ratio 1:2 and severly limits how far the ram can overclock.
 
I have a e6600 cpu with an intel bx2 motherboard. It looks similar to your asus bios. I have 667 memory and like you I set the dram frequency to 667 and the board wouldn't boot. When I set it to 533 it booted so I left it there. Unlike most boards the multiplier on my board can't be changed down so I am stuck at 9. Anyway the memory speed is 2x the fsb so when you set fsb to 300 and it showed up as 300 in the cpu-z memory section, 2x that is what your memory is actually runningI don't know how high you can go on the fsb but you can drop the cpu multiplier to 10 and then raise the fsb to see how high it will go.
 
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