FSB vs Multiplier

[fx9]

Hi guys,

I have a question here, will my DDR2-800 RAM achieve higher performance with a higher FSB as opposed to a higher multiplier?

For eg. : FSB266MHz x 9
vs FSB400MHz x 6

That's it, which of the settings will make full use of the DDR2-800 bandwidth?
Have a thought bout it

BTW, if i up the FSB without actually increasing the resulting clockspeed, is it considered O.C?
Pls...cuz i wanna avoid the warranty-void issue.

 

[Noubourne]

DDR2 is quad-pumped. Thus, a 200Mhz FSB is always multiplied by 4 to get 800Mhz of the DDR2.

So the higher of a FSB you put (assuming you aren't running a memory divider), the faster your RAM will go.

The multiplier that you change in BIOS is for the CPU core mhz (FSB x Multi = CPU Frequency).

If you run your DDR2 800 too far out of specification, it is likely to throw errors. You'll get more performance overclocking the CPU, which is what most people focus on - using Memory Dividers (133, 166, or 5/6, 9/10 - depends on your BIOS how it gets displayed) to minimize the stress on the memory by running it slower than the FSB by some fraction (9/10 is 90% FSB speed - so on and so forth).

You really need to read some guides to overclocking before you do anything. Ham-handing around in your BIOS is likely to result in an unstable system, an unbootable system (till CMOS is cleared), or worse.

 

[imported_inspire]

Originally posted by: fx9
Hi guys,

I have a question here, will my DDR2-800 RAM achieve higher performance with a higher FSB as opposed to a higher multiplier?

For eg. : FSB266MHz x 9
vs FSB400MHz x 6

That's it, which of the settings will make full use of the DDR2-800 bandwidth?
Have a thought bout it

BTW, if i up the FSB without actually increasing the resulting clockspeed, is it considered O.C?
Pls...cuz i wanna avoid the warranty-void issue.

The CPU multiplier does not affect memory speeds, only the divider you use along with the FSB. So, FSB400MHz x 6 would be faster. If you raise the FSB without increasing the clockspeed, then you're implying that you're lowering the CPU multiplier in the process. (Clockspeed = CPU mult. x FSB). Technically, I would not consider this overclocking your CPU. However, you are overclocking your memory... I'm not sure which warranty you were worried about there...

 

[XBoxLPU]

Originally posted by: Noubourne
DDR2 is quad-pumped. Thus, a 200Mhz FSB is always multiplied by 4 to get 800Mhz of the DDR2.

.

Uh no

DRR2 800 is a FSB of 400

 

[myocardia]

Originally posted by: XBoxLPU

Originally posted by: Noubourne
DDR2 is quad-pumped. Thus, a 200Mhz FSB is always multiplied by 4 to get 800Mhz of the DDR2.

.

Uh no

DRR2 800 is a FSB of 400

That's correct, to run at DDR(2) 800, the FSB has to be at 400 Mhz, or 1600 Mhz, in Intel's terms. But, most of the better motherboards allow running the RAM with a divider (an upward divider, not a downward divider, like is used for overclocking), even though the cpu stays at a 266 FSB.

And no, fx9, with PC 6400 RAM, you wouldn't be overclocking either your RAM or your cpu, if you run at 6x400, instead of 266x9. It also doesn't put any extra stress on the cpu, unless the cpu is an AMD Athlon 64 or Sempron.

 

[Adfaw]

I think that as a rule having a better FSB woudl always be better than just a larger multiplier factor. A higher multiplier factor just has the Celeron or Sempron Processor feel to it, it looks bigger and badder, and it's cheaper, but it's really slower.

 

[Noubourne]

Originally posted by: XBoxLPU

Originally posted by: Noubourne
DDR2 is quad-pumped. Thus, a 200Mhz FSB is always multiplied by 4 to get 800Mhz of the DDR2.

.

Uh no

DRR2 800 is a FSB of 400

As far as I know the memory is actually running 200mhz internally with one group offset from the other group by half a sine wave or so to get the external 400mhz frequency, but in his BIOS he's gonna see 400Mhz, so I'll call you right on that one.

 

[Noubourne]

Originally posted by: Adfaw
I think that as a rule having a better FSB woudl always be better than just a larger multiplier factor. A higher multiplier factor just has the Celeron or Sempron Processor feel to it, it looks bigger and badder, and it's cheaper, but it's really slower.

That's actually not true at all. Multipliers are larger to allow for higher clockspeeds. If you have a 200FSB to the CPU in your typical system, then with a 10x multiplier you get a 2000Mhz CPU speed. If you could set the same chip to use a 12x multi in the same system, you'd get 2400Mhz.

When you buy a faster chip, you're sometimes getting the same chip with a higher multiplier. Some chips have more cache - or two cores instead of one, or four cores instead of two, but lets look at the new Conroes as an example:

The difference between an E6600 and an E6700 is multiplier, and nothing else. For all intents and purposes, they are exactly identical except for the multiplier. The E6600 has a 9x multiplier, and the E6700 a 10x. 9x times the 266FSB speed = 2.4Ghz and E6600. 10x times the 266FSB speed = 2.6Ghz (2667Mhz) and E6700.

They are made from the same wafers in the factory, Intel just locks some down with a The multiplier on the E6600 is locked so you can't get an E6700 for free. If you want to get E6700 speeds, you'll have to up your FSB speed to do it.

Of course other stuff in your computer (hard drives, memory, etc) relies on that FSB speed too, so you have to do some mucking about with other settings and dividers that the mobo manufacturers give you which allow you to overclock the CPU without screwing up anything else. For example, most motherboards "lock down" the PCI Express bus speed so that it is clocked separately from the FSB. This way you don't screw up how data gets sent to your video card while you're trying to overclock your CPU.

And some RAM can be overclocked (or faster RAM is available), so they let you use different dividers to get different speeds of RAM. All these settings are provided to allow the fastest possible system (based on the capabilities of your hardware) if you are willing to put in the time and effort.

 

[cmdrdredd]

Originally posted by: fx9
Hi guys,

I have a question here, will my DDR2-800 RAM achieve higher performance with a higher FSB as opposed to a higher multiplier?

For eg. : FSB266MHz x 9
vs FSB400MHz x 6

That's it, which of the settings will make full use of the DDR2-800 bandwidth?
Have a thought bout it

BTW, if i up the FSB without actually increasing the resulting clockspeed, is it considered O.C?
Pls...cuz i wanna avoid the warranty-void issue.

If you even consider running anything even the FSB out of the standard stock settings you're overclocking something and your warranty is gone.

That being said a faster CPU is ALWAYS better than a higher FSB. For instance if you run 500x6 for 3Ghz CPU you will get better performance from 400x8 for 3.2Ghz CPU. Memory performance always comes second to the CPU and FSB speed is 3rd.