Question about FSB:DRAM ratio

Ok, so you have an Intel Dual Core E5300 CPU. The default front side bus speed of this CPU is 800Mhz. So, first you take the 800Mhz and divide by 4 since the INtel CPU's are quad pumped. (800 / 4 = 200mhz). Therefore, you have a default FSB speed of 200Mhz for your motherboard with a 13x multiplier for an E5300 chip, getting it up to it's default clock speeds (200 x 13 ) = 2,600Mhz.

Now, with Double Data Rate RAM, you take the FSB speed of the mobo (200Mhz) and you double it. (200 x 2 = 400Mzh). Therefore, if you really want a 1:1 ratio, you would be running your RAM at 400Mhz instead of 1,333Mhz...which is probably a lot slower than you want.

You have a few options, use dividers instead of a 1:1 ratio and run your RAM at higher speeds. Or, you have to try to overclock that CPU and get it's FSB increased (a lot). To get a 1:1 ratio with this method, you would have to increase your FSB speed to 667Mhz from 200, but with a 13x multiplier, you would be running at 8.6Ghz. If you can reduce your multiplier, you can lower those speeds...but I'd strongly suggest having a fire extinguisher handy as your chip isn't going to handle that.


I'm running my Q9550 with DDR2 ram at a 1:1 ratio but it is much easier. The Q9550 has a quad pumped FSB of 1333Mhz. (1333 / 4 = 333Mhz). My FSB speed stock is 333Mhz with an 8.5x multiplier. (333 x 8.5 = 2,833Mhz). So, my RAM by default would run at 667Mhz (333 FSB x 2= 667Mhz). So, DDR2-667 would be the appropriate RAM for stock speeds. Well, I used DDR2-800 RAM instead of DDR2-667 and this allowed me to increase my FSB on my mobo from 333Mhz to 400Mhz. So now my CPU runs at 3.4Ghz (400 x 8.5 = 3400Mhz), and my RAM is running at 800Mhz (400 x 2). So, nice and easy 1:1 ratio here.

darko933 said:

Can you please tell me the best overclock for my processor?

No, because every CPU, mobo, memory combination as well as cooling are different. Overclocking is a fine art and you have to tinker to see what your exact hardware can actually do. If you have 5 CPU's that are the same, they probably all would be different with respect to have far you "could" overclock them.