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RAM/FSB question

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July 1, 2008 3:22:52 AM

OK guys, my FSB is 210 MHz, and my RAM is 667. considering that RAM is "Double Pumped", this means that to get 1:1 with my CPU it should be 420? so i could drop the RAM to 420.....(somehow i dont think my mobo can do that but yeah...) and get low timings? or is there something in this that i don't understand? So, my FSB is 210, and my CPU being "Quad pumped" has a "Frequency"? of 840 MHz. this is a kind of confusing topic...

is that whole quad pumped thing "Frequency"? or something else? my CPU has a internal multiplier of 10.0x so therefore it is 2.1GHz (its a core 2 duo)CORE CLOCK? so what is the difference between "FREQUENCY" and "CORE CLOCK"? is "Frequency" the speed at which the cpu communicates with the RAM?

Therefore, does the RAM have a similar thing? is it 667 MHz clock and something else frequency? this is a very confusing topic. Someone please clear up for me i hate being a noob.... :( 

More about : ram fsb question

July 1, 2008 5:26:18 AM

Honestly, you can ignore the QDR junk.

Its just divided by 4 and then you use the FSB frequency for the rest. Your RAM can run with the FSB if you place it on linked mode, then sync mode. It should support any speed that the FSB can do.

So your FSB of 210 Mhz means that the Pathway your RAM has to send data through is restricted to this amount. By using a divider over it, to make it that 667, you may see small gains in synth bench marks, but none in real world junk, baring ddr1 and old junk!

So if you can run your RAM at 420, since it Really is double "pumped" so to speak, because there are two sticks. Always a pair.

In reality, its just half for each. So 210 for each stick for 420. (Or whatever your divider brings it up to.)

And yeah.. I have read junk like warnings that say its not healthy to run it under 533. I am gonna test it in a lil while myself to see.

I would recommend listing your gear, each piece, Mobo type, processor type, etc, so people will know Exactly what you are talking about. ;) 

Think of FSB as your Core clock. Because everything else is based off of it.

Double for your RAM. (Really equal to while in sync, but two sticks.)

Simply times the CPU multiplier for the processor frequency. IE. 210 x 10 Multiplier would be 2100, 2.1 Ghz.

If yours is 210, I wonder what weird old processor you have!

List yer gear!

--Lupi
July 1, 2008 6:19:30 AM

LOL sorry lupi, i was a bit rushed...

OK here's me specs:

Intel core 2 duo E4400 (2.0GHz) @ 2.1GHz (stock cooler)

2GB (2x1GB sticks) Kingston DDR2 667MHz

250GB Seagate something-a-rather (not that it matters...) SATA 1.5Gb/s

LG super multi dvd rom etc...

Palit 7600GS Sonic 256MB GDDR3, 400/500 clocks (doesnt have a shader thing in ati tool lol) OC'd to 600/750 stock cooler

some really crap 430W PSU

some old ATX case we had lying around...

ASROCK 4-core-dual-vsta (stupid name...) supports quad cores up to 1066 MHz FSB (something im confused about...) AGP8x and PCI express 4x, SATA 1.5GB/s, 2xDDR 400, 2xDDR2 667


OK, so i assume by your first paragraph that you mean the CPU FSB (or whatever its called...) of for example 800MHz in my case divided by four... i overclocked it to 210 in the bios so that means 880MHz Frequency for the CPU? So then frequency is the speed at which the cpu communicates with the ram? or does it do something else? or is it in fact something other than "FREQUENCY"

Erm, what do you mean by "by using a divider over it"? wats a divider....do you mean the whole doubel pumped thing?

And i thought FSB was different to core clock, as the core clock is the result of the FSB multiplied by the internal multiplier [of the CPU]!!

err please clarify lupi?
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July 1, 2008 6:32:04 AM

CPU frequency? That is the speed at which the cores opporate. It is expressed as a frequency, because that is exactly what it is. It cycles at xxx hertz, just like any other wave pattern.

As for the FSB. That is the pathways your system communicates with the ram.

Damn, i will do your reserch for you. Core 2 duo 4400. Uses a x 10 Multiplier with a 200 FSB to equal 2.0 Ghz.

Your FSB is 200. That means 400 for RAM, since it doubled. Because your ram is "rated" for a speed faster, it uses a divider to get that rated speed. So its the FSB doubled, then whatever divider to give you the speed.

Just as its the CPU Multiplier x the FSB to give you your processor speed. or Frequency, as it is.

Specifically, the divider is the number x the FSB to equal your rams speed. In sync would equal your ram speed. If it is not in sync, then it can apply different dividers to get the speed. IE. 1:1 or sync mode would be double the FSB, since there are two sticks of ram. But to get a higher speed, like 800 Mhz standard, it would use a 1:2 divider. Doubling the FSB to equal 800. (Since it is x 2, because its dual channel.)

So yours would use some weird 5:13 or berserk divider to get 667. I hate doing that, and I never use less than 800 Mhz!

Ideally for your RAM, you'd want a 333 Mhz fsb. As double that would be your RAMs rated speed.

If it's not double the FSB, the bios applied the right divider to get it as close to 667 as possible. Sometimes that can be very bad, hehe!

Hope that helps!

--Lupi
July 1, 2008 6:39:13 AM

That sounded confusing even to me.

A divider. Used to give RAM its speed.

FSB x Divider then double for double data rate = speed.

Sync mode would always match the FSB. But may appear as either 200 Mhz, or 400 Mhz. Either way, it is because each stick is the FSB speed. But you have two of them.

If you have that 667 ram and a 200 FSB it uses some weird divider to get the nearest speed.

It's always the FSB Times the Divider to get the speed.

Gawds, how do you explain that to someone, hehehehe?

Help!

Save me, Oh green man!

--Lupi
July 1, 2008 7:19:59 AM

OK lets make this simple.

CPU:
CPU FSB: This used to calculate everything through the system.
QDR FSB: On Core 2s this is always CPU FSB x 4
MULTIPLIER: The number by which the CPU FSB is multiplied to get your final CPU FREQUENCY.
CPU FREQUENCY: CPU FSB times MULTIPLIER

Memory:
FREQUENCY: The speed at which the memory runs at. With DDR2 its always double of the "MEMORY FSB". With DDR3 its 4 times higher.
MEMORY FSB: The speed of the memory.
DUAL CHANNEL: Two memory chips are synchronized to simulate one double sized/double speed(in theory) memory chip.
MEMORY DEVIDER: Its used to work out the memory FSB from the CPU FSB.

You said your CPU has a multiplier of 10 and a frequency of 2ghz. So 2000mhz (2ghz) / 10 = 200mhz (your FSB). 200 x 4 = 800 your QDR FSB.
You also said that your memory speed is 667mhz(so your memory FSB is 333mhz) and your memory devider is 5:8. That devider means that for every 5mhz on the CPU FSB you'll get 8mhz on the memory FSB.

Sadly the weakest link rule applies so your maximum effective memory speed is 200mhz (CPU FSB since its the lowest FSB) x 2 (since your using DDR2) x 2 if your using DUAL CHANNEL. That gives a maximum of 800mhz transfer speeds between your CPU and memory. Then you said you overclocked your CPU from 200mhz CPU FSB to 210mhz. That also raises your memory from 667mhz to 733mhz. Sadly your CPU FSB still runs at 840mhz (210mhz times 4 to get your quad pumped data rate or QDR FSB)
July 1, 2008 8:28:22 AM

::Grins.::

Hehe, thanks.

:) 

--Lupi
July 2, 2008 1:51:44 AM

yeah lupi lol "Damn, i will do your reserch for you. Core 2 duo 4400. Uses a x 10 Multiplier with a 200 FSB to equal 2.0 Ghz." i did say i OC'd it to 210 FSB...

OK, so im still confused a little bit: you get your FSB right (eg 200) and multiply it by four to get QDR FSB. SO, what exactly is this QDR FSB? is it the speed the cpu communicates with the RAM, or is it something different???

So, is the CPU FREQUENCY is just another word for its CORE CLOCK? or something different again...

And, there is two types of "FSB" with the CPU: core clock or "frequency" and the QDR:the speed at which the CPU communicates with the RAM?

Therefore, i would assume there would be something the same with the RAM, or is there simply one calculation, and it is purely the speed at which it communicates with the CPU? so there is no calculation to give a RAM version or the CORE CLOCK/FREQUENCY?

very technical topic LOL... or maybe im just an uber noob :( 

oh and btw lupi, there is no way in hell im gonna get 333MHz FSB on my board... :( 
July 2, 2008 11:34:51 PM

QDR is a wasteful way to get your FSB. (And the way Intel lists its FSB rated speed for a chip.) Ignore QDR, and just divide it by 4 to get the actual system FSB.

QDR is a bogus term. The RAM uses the FSB.

You might as well try for the highest FSB your system can handle.

Uhhh.. The FSB is the way you calculate the processor speed, and the RAM speed.

FSB x the Multiplier = CPU speed. (Whatever you wanna call it!)

FSB x the divider = Memory speed.

It's that simple.

Though with RAM there are several options for the divider. Most stick with Sync Mode because it runs at the "natural" speed of things. IE, the FSB.

--Lupi
July 3, 2008 10:08:00 AM

OH LOL!! I GET THE WHOLE DIVIDER THINGY!! its the 1:1 or 6:7 etc.... i knew what it was but i didnt know it was called a divider lol...thanks a lot lupi that really cleared it up. i think.
July 3, 2008 10:11:52 AM

i hope thats wat the divider is anyhow...
July 29, 2008 6:25:18 AM

Wow, this question garnered the most confused and confusing responses I've ever seen from Lupi!

To try to clear things up - there is one FSB. Only one. It is set in the northbridge chip. The CPU frequency and memory frequency are derived from this one FSB.

It sounds like you figured the FSB out. But Lupi mucked up the explanation of the memory speed ratings. Those ratings, like 667, 800, etc, are the Double Data Rate ratings (that's what DDR stands for - double data rate). The way DDR works, it sends information both on the rising and falling edges of the clock signal from the FSB. So they rate the memory at twice this speed to indicate that the total number of transactions per second is twice that of the clock signals it receives.

Unfortunately, the memory dividers make things slightly more complicated. It turns out that you can alter that FSB signal with the dividers to send the memory a higher (or lower, I guess) clock frequency, which means that it will be able to send data on the rising and falling of those faster clock signals, effectively increasing the bandwidth of the memory to twice the FSB speed after the divider. As it happens, there is seldom any tangible increase in performance associated with using a higher memory divider. This is in part due to the fact that the northbridge chip now has to bump frequencies up and down, and also try to stuff the data from the memory into a lower clock speed, which can cause a bottleneck. I suppose that theoretically, if you could run your memory with a 2:1 divider (i.e. memory frequency = 2x FSB frequency), that would correspond perfectly with the CPU's QDR and would provide a quite substantial performance boost, but this just isn't realistic with DDR2.

QDR is the way the CPU communicates with the northbridge chip (and memory controller). It has two clock signals which are 90deg out of phase and data is sent on the rising and falling edges of both clock signals.

Dual channel memory only has the theoretical ability to increase the bandwidth to the memory, allowing both sticks in the dual channel setup to send/receive data in the same clock. This doesn't increase the frequency of the data transfer for the RAM, so it shouldn't affect the rated speed of the memory in any way.

At least the CPU multiplier was explained correctly. The CPU core frequency is simply the CPU multiplier * FSB frequency.

The memory divider is typically referenced by things like 1:1, 6:7, so yes, that's what you're seeing in the BIOS :) 
July 29, 2008 9:02:03 AM

Quote:
Wow, this question garnered the most confused and confusing responses I've ever seen from Lupi!

To try to clear things up - there is one FSB. Only one. It is set in the northbridge chip. The CPU frequency and memory frequency are derived from this one FSB.

It sounds like you figured the FSB out. But Lupi mucked up the explanation of the memory speed ratings. Those ratings, like 667, 800, etc, are the Double Data Rate ratings (that's what DDR stands for - double data rate). The way DDR works, it sends information both on the rising and falling edges of the clock signal from the FSB. So they rate the memory at twice this speed to indicate that the total number of transactions per second is twice that of the clock signals it receives.

Unfortunately, the memory dividers make things slightly more complicated. It turns out that you can alter that FSB signal with the dividers to send the memory a higher (or lower, I guess) clock frequency, which means that it will be able to send data on the rising and falling of those faster clock signals, effectively increasing the bandwidth of the memory to twice the FSB speed after the divider. As it happens, there is seldom any tangible increase in performance associated with using a higher memory divider. This is in part due to the fact that the northbridge chip now has to bump frequencies up and down, and also try to stuff the data from the memory into a lower clock speed, which can cause a bottleneck. I suppose that theoretically, if you could run your memory with a 2:1 divider (i.e. memory frequency = 2x FSB frequency), that would correspond perfectly with the CPU's QDR and would provide a quite substantial performance boost, but this just isn't realistic with DDR2.

yep yep know all that...

Quote:
QDR is the way the CPU communicates with the northbridge chip (and memory controller). It has two clock signals which are 90deg out of phase and data is sent on the rising and falling edges of both clock signals.
Quote:


hmm this was the only bit i still didnt understand but i didnt want to bug lupi anymore, lol
doesnt it have 4 clock signals? "quad pumped"? and wtf is that 90 degrees out of phase thing! O_O :ouch: 

Quote:
Dual channel memory only has the theoretical ability to increase the bandwidth to the memory, allowing both sticks in the dual channel setup to send/receive data in the same clock. This doesn't increase the frequency of the data transfer for the RAM, so it shouldn't affect the rated speed of the memory in any way.

At least the CPU multiplier was explained correctly. The CPU core frequency is simply the CPU multiplier * FSB frequency.

The memory divider is typically referenced by things like 1:1, 6:7, so yes, that's what you're seeing in the BIOS :) 

yep yep know all that too lol, funny the amount you can learn in like 2 days of forum posts! i had gone from not even knowing what QDR stood for to this! :bounce:  :bounce:  :bounce:  :bounce: 
July 29, 2008 4:42:10 PM

That's good, and from seeing your more recent posts, I figured you did know these things, but in case someone else stumbled upon the thread, it would have been horribly confusing and even incorrect... Not very helpful to new people who follow our advice and actually read through other threads before posting their "how do I overclock" thread.
July 30, 2008 5:51:25 AM

lol yeah good point :) 
!