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post #21 of 27
DUh, the tapping is a rather loose analogy to try to illustrate my point.

Quote:
When looking at the bandwidth in terms of MB/s, your memory needs to be operating 2 times as fast as the CPU's FSB in order to match the CPU's L2 bandwidth.
How could RAM ever match the CPU's L2 bandwidth, unless you mean bus width? L2 runs at full core speed, and has much lower latencies than main RAM, and will consequently significantly outperform it. Maybe I misunderstood.

Scupkin, it looks like 666 is faster for you. On my system, 576 is WAY faster than 720 (666 divider). My theory must be true for crap chipsets like mine. I'm sure the i945 you have is much better designed to actually take advantage of the extra ram speed regardless of the FSB.

Any explanations, pauldovi? The first picture is 576 3-3-3-8 1T on a 1:1 divider, and the second is 720 4-4-4-10 2T with the 666 divider (4:5 I think). For some reason CPU-Z doesn't understand the RAM dividers on my mobo, but I promise you it is set to 666. The CPU clock is unchanged.

    
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post #22 of 27
Quote:
Originally Posted by RADEON View Post
DUh, the tapping is a rather loose analogy to try to illustrate my point.



How could RAM ever match the CPU's L2 bandwidth, unless you mean bus width? L2 runs at full core speed, and has much lower latencies than main RAM, and will consequently significantly outperform it. Maybe I misunderstood.

Scupkin, it looks like 666 is faster for you. On my system, 576 is WAY faster than 720 (666 divider). My theory must be true for crap chipsets like mine. I'm sure the i945 you have is much better designed to actually take advantage of the extra ram speed regardless of the FSB.

Any explanations, pauldovi? The first picture is 576 3-3-3-8 1T on a 1:1 divider, and the second is 720 4-4-4-10 2T with the 666 divider (4:5 I think). For some reason CPU-Z doesn't understand the RAM dividers on my mobo, but I promise you it is set to 666. The CPU clock is unchanged.
No, the L1 runs at the "full" CPU speed. Your L2 cache is running at the speed of the FSB. The memory communicates with the FSB. The instructions are actually calculated within the L1 cache.

http://www.overclock.net/intel-cpus/...rclocking.html

Quote:
Originally Posted by pauldovi
The CPU

Your CPU has a FSB (front side bus), which is the speed it communicates with the memory and north bridge. In an Intel system, your FSB is quad pumped, meaning that you multiply the actual FSB times 4 to get the rated FSB. What this mean is that your CPU's front side bus sends 4 transmissions of data per clock cycle. This is analogous to memory which can transmit 2 pieces of data per clock cycle (DDR or Dual Data Rate). Instead, the FSB is QDR (Quad Data Rate).

For example:

266.66Mhz FSB x 4 = 1066Mhz rated FSB.

The FSB is the speed of the L2 (level 2) cache. L2 Cache is largest chunk (desktop CPUs only) of memory on the CPU. This is what directly communicates with your system memory. From the L2 cache the data is moved to the much smaller, but also much faster L1 (level 1) cache. CPU speed is normally referred to as the speed of the L1 cache.

In order to determine your CPU speed, you multiply the FSB by its multiplier.

For example:

266.66Mhz FSB x 9 = 2.40Ghz

The 2.40Ghz is the speed of the L1 cache.

Normal Intel processors are limited to their stock multiplier. They can go down multipliers if their motherboards support it, but they cannot increase in multiplier. This is intentionally done by Intel to prevent system vendors from buying cheaper processors and manually increase the multiplier and selling it as a faster system. However, some ES (Engineering Sample) and all XE (Extreme Edition) processors have unlocked multipliers. You can manually increase or decrease the multiplier on the system (to an extend). You will pay a premium price for this capability.
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post #23 of 27
Quote:
Originally Posted by pauldovi View Post
No, the L1 runs at the "full" CPU speed. Your L2 cache is running at the speed of the FSB. The memory communicates with the FSB. The instructions are actually calculated within the L1 cache.

http://www.overclock.net/intel-cpus/...rclocking.html

L2 has been full speed ever since Coppermine way back when ever it was. Since when did they switch over to running it slower? I want

I don't doubt your expertise. I'm just kind of shocked. I just took full speed L2 as a given ever since the slot CPUs went south.

My chip is a Prescott. I thought at least they still ran it at full CPU speed.

My screenshots still prove your "faster RAM performs better" theory wrong, though. Any ideas why?
    
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post #24 of 27
Quote:
Originally Posted by RADEON View Post
L2 has been full speed ever since Coppermine way back when ever it was. Since when did they switch over to running it slower? I want

I don't doubt your expertise. I'm just kind of shocked. I just took full speed L2 as a given ever since the slot CPUs went south.

My chip is a Prescott. I thought at least they still ran it at full CPU speed.
3.0Ghz P4 630

L2 = 2MB @ 800Mhz
L1 = 12+16KB @3000Mhz
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post #25 of 27
According to sandra, my L2 cache is full cpu speed. Is FSB speed L2 a C2D thing, or something?


    
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post #26 of 27
dont stop at 333 tell us what u get on a 945 chipset and also dont underestimate ur ram cuz my crucial rendition stick clocked to 520mhz (ddr2 1000) stabily and it was cheap "mwave brand" ram
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post #27 of 27
Sandra isn't perfect you know.

Think if it logically.

You go from a not so fast very large HDD to a smaller (but faster) DDR2 memory. Then that data goes from the large DDR2 memory to the much faster (and smaller) L2 cache. From there continues: smaller and faster.
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