Originally Posted by krishancanag
excellent post, I understand what you are saying, what I still don't undertsand though is what is going on in the 2 examples I picked off from abit, why is the higher RAM speed got a lower FSB and vis-a-vis. When as you say balancing both is ideal.
A FSB of 333MHz (1333/4) should run perfectly with 667MHz DDR2 RAM, 1:2
Yet if you look at the 2 examples and see thr ratio's and the speeds, it does not add up, so I think still there is a lack of understanding as to how the calcuations work.
Could it be like this!!
fsb = 1333 = 333mhz
ddr2 @ 800mhz
333*6 : 400 *5
1998 : 2000 approx matched
fsb = 800 = 200mhz
ddr2 @ 800mhz
200*2 : 400 * 1
WHAT DO YOU THINK!!!
Have I cracked it
I'm not sure what you mean by your ratio's...
How it works, is that, your motherboard "detects" the fsb boot strap. Some do a better job than others.
What happens is that your motherboard is auto detecting your ram and cpu settings... This isn't a good thing with an enthusiast board...
If you have a 333fsb, and the board "detects the chip as a 266fsb cpu, then the boot strap gets all waked out when it finds your ram speed and throws in some strange memory divider to get the rated speed from the memory's SPD...
You want to go into the bios and manually set a lot of the cpu, ram, boot strap, divider settings so it actually matches what the hardware is...
Sometimes when a motherboard "supports" a high fsb like 1333 they may not have the bios figured out at shipment, and the board only supports the 1066 boot strap, but can OC your 1333 chip... Later, the board manufacture will come out with a bios that supports the 1333 boot strap, and the diver wont freak out so much...
look at the boot strap settings in your bios, you should see these numbers:
200 = 800fsb
266 = 1066fsb
333 = 1333fsb
400 = 1600fsb
If you select a 1066fsb cpu, to a 400fsb boot strap, your still maintaining the 1:1 memory ratio, and achieving a 800mhz oc from your cpu...
The reason why people like the X38 boards, is because it supports the 1600fsb CPU's. the boot strap is 400mhz so when you set a slower fsb cpu to the higher 400 boot strap, you get a nice oc out of your cpu, and keeping the DDR2-800 speed of your ram.
so, if you have a 1066fsb cpu, and run it at the 333 boot strap, you get an oc, but your not going to be able to run your ram at 1:1 at the ram's advertised speeds... your DDR2-800 ram will now be running at 667 with this setup... You would need to overclock your ram, to 1066 so that when you take in to affect the boot strap settings, you will achieve the DDR2-800 speed of your ram... At 1:1 ratio...
You can always divide your ram to a few different settings, and some boards do this automatically to get the "best" ratio with the selected boot strap. If the board detects your CPU with a different boot strap than it really has, then a number of things can happen. Ether a slower CPU speed by default to keep your ram speed at a 1:1 ratio, or your board might do something strange with the ratio to maintain the CPU's real speed but with a slower fsb rating....
A lot of things happen when a board can figure out the best default settings, thats why its always recommended that a user go into the bios and manually set the speeds of everything.... Even if your not overclocking.
But thats the name of the game here, OC the crap out of it!!!