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FSB:DRAM?

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April 30, 2006 10:31:27 AM

Looking at Cpu-Z in the memory section, what's FSB:D RAM means? :?

More about : fsb dram

April 30, 2006 10:45:27 AM

I got 12:5

Anyways my system is:

Pentium D 840 3.2Ghz overclocked to 3.8Ghz, from 800 to 950mhz bus speed, multiplier x16 and FSB 237.5mhz

4x512 XMS2 DDR2 533Mhz 3-3-3-8-11 2T to 400Mhz 3-3-3-5-10 2T

Is that good, okay or bad? And how could I change it?
April 30, 2006 11:45:24 AM

I got 1:1 with 800fsb and 400mhz mem.

200MHz quad pumped to 800 CPU
200MHz double data rate 400MHz memory

It's the FSB to memory ratio.

http://www.obm.co.nz/OBMNew/800x600/guides/ddrram.htm
Quote:
Memory Clock (100/ 133/ 166/ 200 MHz) (DRAM Clock) (1:1 DRAM:FSB)
Specifies the clock speed of the memory bus. This rate is normally specified relative to the front-side bus (FSB) clock. DDR technology (double-data rate) doubles the data rate given by the actual bus clock speed.

Note: On AMD XP systems, often the best results are obtained with a 1:1 ratio with your FSB frequency. eg. CPU FSB 166Mhz(333):Ram clock 166Mhz (pc 2700 ram). Running a faster memory clock speed than your FSB speed can reduce performance. Instead, you'll probably get better results from optimizing the timing parameters. Use a Memory Diagnostic or Benchmarking application to find the best solution for your system.
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April 30, 2006 11:47:09 AM

the FSB:D RAM is the speed divider between the FSB and DRAM so they work at a ratio of 12:5 in your case so if to make things simple, your FSB is at 120MHz, your memory should be running at 50MHz(thuugh I hope this isn't the case). On my computer it is 1:1 because my FSB is at 1066 MHz and my memory is also at 1066 MHz. This ratio is used mostly for overclocking either your memory or cpu in the bios and you know that the other is going to hold you back i.e. your 400MHz memory on a divider of 1:1 will blow up if my computer tries to run it with my CPU FSB at 1066, so I would set the divider to something like 1:3 so my CPU runs at 1066MHz and my memory runs at 355 MHZ just as a simple example.
April 30, 2006 11:59:23 AM

So, is there a way to improve this settings to make them to a closer ratio?
a b } Memory
a b à CPUs
May 1, 2006 7:30:28 AM

950 to 237.5 IS a 1:1 ratio. 237.5 would be DDR475, in dual channel it would have the same bandwidth as your 950 CPU bus.

Your CPU is running on a 237.5 x4 data rate, your RAM is running at 237.5 x2 data rate, so they're both at the same frequency, and dual channel mode makes up the difference between the x4 and x2 data rate.

You're golden, try to find the lowest possible timings at your current frequencies.
May 1, 2006 8:20:11 AM

Cool..thanks for the info. Anyways at stock settings the ram is suppos to be 3-3-3-8-11 2T and at 400 automatically adjusted to 3-3-3-5-10 2T. I don not know if I could go any lower than 3 or I don't know what's the best timing. I don't even know what's this numbers exactly mean but for one thing I know its' better to have the lowest ones. :) 

Right now it's 3-3-3-5-10 2T, so which one should I change the 3's or the 5 or the 10? I'll give it a shot...
a b } Memory
a b à CPUs
May 1, 2006 8:58:55 AM

You might be able to drop it to 1T. You might need to raise your RAM voltage to make it work at 1T.
May 1, 2006 9:21:50 AM

From what I've know with Intel 4x512 Mb ram can only be stable at 2T. I tried is several times with normal voltage of 1.8 at 1T and I get crashes. If you could help me run my rams at 1T that would be awesome and how much performce is that from the 2T?

Anyways I have not manage to tighten the timings but I've increase the ram frequency from 400 to 450.


The new settings:


CPU:

Core speed: 3800Mhz
Multiplier: x16
FSB: 237.5Mhz
Bus Speed: 950.0Mhz

RAM:

Frequency: 110.8Mhz
FSB:RAM: 15:7
Timings: 3-3-3-6-12 2T

Is this a good improvement from my last settings?
May 1, 2006 10:37:54 AM

Okay I set the ram back to 400Mhz and manage to set the timings at 3-2-2-5-12 2T, however no luck with setting the clock cycle to 1T at 1.9v for it won't boot at all.
!