On the RAM bandwidth

[xsquare]

I am running a DDR2 RAM at its maximum frequency of 533 MHz, while the frequency of FSB is 200 MHz. Thus, the bandwith between the CPU and RAM through the FSB should be 266 (RAM frequency) x 2 (multiplier for the Double Data Rate) x 8 (width of FSB) = 4.3 GB/s (approximately). But when testing the bandwidth with SiSoftware Sandra I am getting 3.6 GB/s bandwidth which is much lower. How can this be? Why am I getting a lower frequency in my benchmark?

 

[ShrimpBrime]

This is because the ram is running half of it's native frequency.

It would probably be better to OC from the 400mhz (ddr2-800)divider to reach 533mhz - 600mhz effective is common on water cooling the Cpu if you can get the bus clocks from it.

So it's actually labeled PC2-1066 memory and should run effective 533mhz.

EDIT
Wait NVM. Your native ram freq is NOT 533 but 266. You need a better set of Ram IMO. Look for DDR2-800 sticks or 533 (PC2-1066)

 

[Jognt]

Please note that 4300MB/s is the maximum theoretical throughput you can achieve.
There are always two points to keep in mind when testing based on theoretical maximums:
1. It's theoretical. In real world scenarios you will probably see something like 50%-80% of that value.
2. The numbers you see after benching depend on the software you use. Programs like SiSoftware Sandra show you theoretical performance, not real world. So these benchmarks can be misleading when comparing bench data with real world application performance.

I have been out of the whole OC scene for a bit too long, so I can't directly say whether your score is bad or not. Perhaps it could have been higher, but I am not sure.

Also, take a look at: http://www.maxxpi.net/pages/downloads/maxxmemsup2---preview.php
It may give you more information to compare to.

I just ran MaxxMem and the results were between 20k and 23k MB/s with 53ns latency on my ram. Considering my RAM has a theoretical bandwidth of 10.700MB/s, but is running on dual channel, those numbers line up pretty good. (10.7k * 2 = 21.400MB/s, right between the various benchscores).

Since my signature has not been updated to reflect the advancement of time, here's my current PC:
Intel core i5 3570k @ 4.3GHz
2x4GB Crucial DDR3-1866
GTX670 SLI
Crucial M4 256GB SSd
Asus P8Z77-V