Max FSB not compatible with memory?

falconzfan007

Distinguished
Jul 19, 2008
61
0
18,630
For DDR3 memory, I heard that you divided the MHZ by 4 to find the maximum FSB that will work when you overclock. So if i have 1600 MHZ RAM (Which i believe is the highest), the highest FSB i can have is 400? And with a Q9550 locked at 8.5x multiplier, does that mean i cant go past 3.4 GHZ?? that doesnt make sense...
Can someone please help me out? thanks!
 

Dekasav

Distinguished
Sep 2, 2008
1,243
0
19,310
You heard wrong. DDR(1/2/3) are double pumped, not quad. Your FSB is quad-pumped.

So at 400Mhz FSB, you run an effective 1600Mhz FSB, and run DDR1/2/3 at 800Mhz (at the standard, usual, 1:1 ratio)

Basically, you can pump your FSB as high as you want, because your CPU or Motherboard won't make it to 800Mhz base FSB. (This is why I have no idea why anyone uses DDR3 for Core 2's)
 

falconzfan007

Distinguished
Jul 19, 2008
61
0
18,630



so that means i am using a 1333 mhz DDR3 RAM, i can have a FSB of 666 and have a 1:1 ratio? im not really understanding the whole double pumped/ quad pumped thing. You said "So at 400Mhz FSB, you run an effective 1600Mhz FSB, and run DDR1/2/3 at 800Mhz (at the standard, usual, 1:1 ratio)." So with a 400 Mhz FSB, how can i run a 1600Mhz FSB?
 
1:1 is overrated too though. Go as high as you can with the FSB, and then pick a RAM ratio that will get you closest to DDR3-1600. You don't want to go under 1:1 typically, but there is no reason to underclock your RAM that drastically just to achieve a 1:1 ratio.
 

falconzfan007

Distinguished
Jul 19, 2008
61
0
18,630


How exactly do I acheive a 1:1 ratio with DDR3-1333 RAM?
 

falconzfan007

Distinguished
Jul 19, 2008
61
0
18,630



When you say 667 base clock, are you refering to the FSB of the processor? Because thats really high when i use my 8.5x multiplier.
 

Brandon00000

Distinguished
Apr 3, 2009
37
0
18,530


all you have to do is unlink it then you can increase your fsb as much as you like just keep your ram at max speed and make sure in the bios you have it selected to unlinked instead of linked then when you increase you fsb your ram will stay the same