Originally posted by: Gusty987
Currently I have my E4300 at 2.7ghz (9x300mhz), and DDR2 at 800mhz (2.66x300mhz) for a FSB:RAM ratio of 3:4.
Now I've read its better to run a 1:1 ratio, is this true? If so, what configuration of multi's and FSB would be best? My mobo is a 965P-S3.
So since DDR2 runs at 2x the bus speed and the CPU clockspeed is 4x the bus speed, if you ran 1:1 ratio (is that what "linked" means, btw?), at 300MHz you'd only be running the memory at 600MHz, so you're bumping it up an extra 25% with the 3:4 divider to get it to 800MHz, correct?
If that's the case, the first thing I would do (if you don't already know it) is to find the highest MHz clockspeed the CPU can run stably. If the max stable speed is 2.7GHz, then at 9x multiplier you can't get beyond the 300MHz fsb you're running now. So lower the multiplier on the CPU. Then you can push up the fsb speed further, which would allow you to run the RAM 1:1 and be closer to 800MHz.
For example, the E4300 is a 9x multiplier, so at 300 fsb, you're running it at 2.7GHz, but if you dropped the mult to 8x, the CPU would be at 2.4GHz (8x300). If your motherboard is a decent overclocking board, you should be able to push it upwards of 400MHz fsb. 350 fsb, for example, would put you at 2.8GHz when using an 8x multiplier. If your board and RAM are both good upward of 400fsb, drop the CPU multiplier further so you can keep going up with the fsb (e.g. 7x386=2.7GHz, 6x450=2.7GHz).
But you also need to know your RAM's max stable MHz as well. If your RAM can't handle 450MHz 1:1 (which would be 900MHz for it), you aren't going to be able to use 6x450 even if your board could handle it.
It's basically a balancing act between fsb speed, cpu multiplier, and RAM ratio, based on the limitations of your CPU, motherboard, and RAM.
The goal being to get the highest combined performance from the three that is stable, with the multiplier being the least important (meaning you can run a lower multiplier without negatively impacting anything (afaik).
So if you have an awesome motherboard that allows high fsb speeds, drop the CPU multiplier and run the RAM 1:1 as high as the RAM can handle. Just drop the CPU multiplier by one anytime you are about to cross the CPU's known max clockspeed threshold (2.7GHz in our example). Of course it is highly unlikely you can get the max performance out of all three, but CPU clockspeed according to most folks is easily the least important if you're already oc'ing it quite a ways (a couple hundred MHz on the CPU is an easy sacrifice to be able to run the fsb and RAM at a higher MHz).
If you have good RAM, you'll be able to push that pretty high, and you can always drop the CPU's multiplier to keep the CPU's clockspeed down into the realm it can handle.
To return to the hypothetical one more time, where your CPU is maxed out at 2.7GHz and your RAM maxes out, say, at 850MHz (2x425) (your board being able to handle more than the RAM in this hypothetical), you would still have several options:
1 - Go with 7x386 for 2.7GHz (max CPU oc), which puts the RAM in 1:1 at 772MHz.
2 - Go with 6x425 for 2.55GHz CPU, max RAM oc 1:1 850MHz.
3 - Go with some combination of RAM divider and CPU multiplier that allows you to get the RAM and CPU both closer to their max OCs. I hate math and don't want to start trying to figure that option out, honestly.
Performance wise, most people assume option 2 or 3 would be better than option 1, and would willingly trade 150MHz of CPU speed for higher RAM/fsb speed.
This is an area that needs more testing, especially on newer systems like 650i and 680i, because I don't think we have a lot of solid evidence as to what is truly the ideal way to go (CPU speed, RAM MHz, RAM 1:1, fsb MHz, or some combination of two or three of those four).
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