Memory: Dividers, Latencies, and Bandwidth Explained - Page 3 - Overclock.net

pauldovi · 06-25-07

Quote:

Originally Posted by redsox83381

So I should run my ballistixs as high as possible as long as I can keep 4-4-4-12? I havent tried any tighter timings....

Well for example, DDR2-800 @ 4-4-4-12 has the exact same latencies as DDR2-1000 @ 5-5-5-15 (30 nano seconds). However, DDR2-1000 has a much higher bandwidth than DDR2-800, so it is better.

funkycasey · 06-25-07

Quote:

Originally Posted by redsox83381

So I should run my ballistixs as high as possible as long as I can keep 4-4-4-12? I havent tried any tighter timings....

Well, he said that timings don't play a HUGE part in it...so you could relax them a bit more to get to a higher MHz...or just bump the voltage up another step... but be careful with the voltage.

pauldovi · 06-25-07

I am going to revise some of the guide because I think it is confusing people.

Ninja_Boy · 06-25-07

An exact guide, so, you want to run your FSB : DRAM Ratio in a 1:2 not 1:1. I have DDR2-800 Ram and a Core 2 Duo so I'd want 266FSB (QDR; Stock) and DDR2-1066.

DDR2-1066 = 5-5-5-15 (30 cycles per operation)
DDR2-800 = 4-4-4-5 (17 cycles per operation)

Quote:

Originally Posted by pauldovi

DDR2-800 does 800,000,000 cycles per second. Latencies of 4-4-4-12 add up to 24 cycles per operation of latency. Divide 24 cycles of latencies by 800,000,000 cycles and you get 30 nano-seconds worth of latencies per operation.

DDR2-800: 800,000,000 / 17 = 47,058,823*
DDR2-1066: 1,066,666,666 / 30 = 35,555,555*

So, DDR2-800 would be better for my situation?

NiNja

*I divided wrong.

pauldovi · 06-25-07

Quote:

Originally Posted by Ninja_Boy

An exact guide, so, you want to run your FSB : DRAM Ratio in a 1:2 not 1:1. I have DDR2-800 Ram and a Core 2 Duo so I'd want 266FSB (QDR; Stock) and DDR2-1066.

DDR2-1066 = 5-5-5-15 (30 cycles)
DDR2-800 = 4-4-4-5 (17 cycles)

The DDR2-800 Ram would be in a 1:1 (400FSB; 6 Multipler).

Which would be faster?

22.5 ns versus 21.3 ns.

Depending upon the application either may be faster. You will probably not notice the difference either way.

Ninja_Boy · 06-25-07

I edited my post, but, realisticly how big is the difference between 3224MB/s of Memory Bandwidth and 4047MB/s of Memory Bandwidth in gaming?

NiNja

pauldovi · 06-25-07

Quote:

Originally Posted by Ninja_Boy

I edited my post, but, realisticly how big is the difference between 3224MB/s of Memory Bandwidth and 4047MB/s of Memory Bandwidth in gaming?

NiNja

Depends on the game.

In games like FSX and SupCom, it probably will make a difference.

Why would you not go for the maximum performance?

Ninja_Boy · 06-25-07

I merely asking, because I want to see if it's a noticeable difference, or a difference of 250 points in 3DMark06. Wait... In my post and in your quote the numbers are different. In my post DDR2-800 is on top, but in the quote DDR2-1066 is on top. So, which one would be faster?

Quote:

Originally Posted by pauldovi

22.5 ns versus 21.3 ns.

Depending upon the application either may be faster. You will probably not notice the difference either way.

Quote:

Originally Posted by pauldovi

Depends on the game.

In games like FSX and SupCom, it probably will make a difference.

Why would you not go for the maximum performance?

LawL.

NiNja

pauldovi · 06-25-07

Quote:

Originally Posted by Ninja_Boy

I merely asking, because I want to see if it's a noticeable difference, or a difference of 250 points in 3DMark06. Wait... In my post and in your quote the numbers are different. In my post DDR2-800 is on top, but in the quote DDR2-1066 is on top. So, which one would be faster?

LawL.

NiNja

DDR2-800 has lower latency. DDR2-1066 has more bandwidth.

Litlratt · 06-26-07

Quote:

Originally Posted by pauldovi

DDR2-800 has lower latency. DDR2-1066 has more bandwidth.

If I understand this correctly, if both examples were running the same timings, then the latency would be the same.
If you can maintain tight timings and continually increase speed, then performance increases regardless of the divider.

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Memory: Dividers, Latencies, and Bandwidth Explained

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