FSB:RAM Ratio question

[VampD]

If you are running at 2:3 that means that your memory multi is 2.5 right now, which is perfectly fine. Don't get hung up on running 1:1 memory:fsb. Just let your memory run at its stated speed unless you are overclocking the cpu.

It means my memory multi is running at 2.5? I don't understand since 266 x 2.5 = 665. My memory multi running at 3.0 makes more sense since 266 x 3 = about 800ish

 

[VampD]

Umm, I think you might be confused about "memory multiplier".

Okay, I will try to help clarify, but I don't know if this will help:

This is your system now:
FSB: 266MHz
FSB:RAM Ratio: 1.5x
RAM speed: 400MHz (266*1.5)
so its running at DDR2-800 because 400*2 = 800

After overclocking:
FSB = 300MHz
Change FSB:RAM ratio to 1:1
Therefore your RAM speed gets downclocked to 300MHz
so now you're running your RAM at DDR2-600.

In case you didn't know, DDR2 says its running at twice the speed it actually is. So for example on your current system, you bought 800MHz RAM, but the RAM is actually only running at 400MHz. The DDR2 technology enables it to double its output. So if you had DDR2-800 at stock and clocked the FSB to 400MHz, you would have a 1:1 FSB:RAM ratio.

But isn't downclocking my ram to 300 mhz give my system a performance hit? Is the 1:1 really worth it?

Heres what further confuses me
Overclocking Quads on Gigabyte P35-DS3R - Page 2 - Guru3D.com Forums

this guy has a 3.2 multiplier ( I don't even have that option it just has a 3 ) and is overclocked 360 x 9 = 3.2 ghz. He says he has a 1:1 ratio, does that mean his ram is running at 1152 mhz?

has anyone ever used auto for memory multiplier?

 

[veedubfreak]

No, there is no point in running 1:1 unless you are running more than a 400mhz FSB.

 

[VampD]

No, there is no point in running 1:1 unless you are running more than a 400mhz FSB.

hmmm is there a general concensus on this?

 

[veedubfreak]

IF you are running anything LESS than a 400mhz frontside bus then you will be UNDERclocking ddr2 800 memory. So just leave the memory at stock settings or play with the memory modifier and go for 900is-1000ish mhz if the memory will handle it. Once i get my other 2 sticks of ocz so that im running all 4 sticks of identical memory im going to try to push mine up over 1k rather than stick with the synchronous.

 

[VampD]

IF you are running anything LESS than a 400mhz frontside bus then you will be UNDERclocking ddr2 800 memory. So just leave the memory at stock settings or play with the memory modifier and go for 900is-1000ish mhz if the memory will handle it. Once i get my other 2 sticks of ocz so that im running all 4 sticks of identical memory im going to try to push mine up over 1k rather than stick with the synchronous.

What about my statement: It means my memory multi is running at 2.5? I don't understand since 266 x 2.5 = 665. My memory multi running at 3.0 makes more sense since 266 x 3 = about 800ish

I just need to know for clarification, did I make the mistake or did you when you said my memory multi was running at 2.5?

 

[Gabb]

What about my statement: It means my memory multi is running at 2.5? I don't understand since 266 x 2.5 = 665. My memory multi running at 3.0 makes more sense since 266 x 3 = about 800ish

I just need to know for clarification, did I make the mistake or did you when you said my memory multi was running at 2.5?

hmm I'm confused about that myself

 

[veedubfreak]

Yes, you have it right. The memory multiplier depends on the FSB. If you overclock the FSB to 333, then you will need to lower the memory multiplier so that the memory doesnt get overclocked too high.

 

[VampD]

Yes, you have it right. The memory multiplier depends on the FSB. If you overclock the FSB to 333, then you will need to lower the memory multiplier so that the memory doesnt get overclocked too high.

Thanks you've been a big help, I now feel a little more confident in my overclocking plans. I just had a few last questions that have gone relatively unanswered:

1. Why don't more people opt for the lower multiplier/higher fsb overclock? Is there a difference between 7 x 400 fsb, 8 x 350 fsb, or 9x 312 fsb? You have to raise the voltage when you up the fsb or multiplier right?

2. Is downclocking the ram like that one guy said a bad idea to achieve a 1:1 ratio? Exactly how important is this 1:1 ratio?

3. Technically if I dont touch any voltages my computers temps should be the same even with a higher fsb right ( assuming it can handle it )

 

[veedubfreak]

1) people downclock their multiplier because they are dee dee dees, or are just trying to see what the max fsb the board will handle. Theres 0 reason to lower your multi, because a lower multi and higher fsb only causes more stress on the northbridge.

2) yes downclocking your memory just for 1:1 is a bad idea. Running synchronous is pointless when your memory can handle 800mhz+. 1:1 is overrated.

3) Even without changing your voltage on the CPU, your temps will go up when overclocking.