Confused about memory speeds?

  Simsy 11:44 04 Oct 2007


I'm contemplating upgrading, by building my own, something I've done before but not for several years...

I'm getting a bit confused as to how to match components...

Based on budget and speed, I'm thinking of gettting the following processor,
click here
which has a fsb of 800Mhz...

What speed RAM do I need to match this? Unless I'm missing something the fasted I can see is PC2 5300, which has a speed of 667Mhz...

Obviously 800 and 667 don't match. Am I missing something? Do these not to be the same?

Observations and explanations welcome?

(And while I'm here, I dont really have a good handle on the speed of CPUs when they are "Dual core"... I realise that there will be losses because of various internal bits of housekeeping, and architecture etc, but for example is a dual core 1.8Mhz processor basically getting through processing at something approaching the speed of a single core 3.6Mhz?)

Thanks in anticipation,



  howard64 15:08 04 Oct 2007

dual core is fine if the software can handle it. I had a fast AMD single core at 4200 then got a core2duo Intel and was surprised to find each core at 1800. When single tasking it was very much slower than the AMD. When multi tasking it was quicker. Look at the mobo spec you are thinking of buying and then enter that info into the site it will tell you what memory can be used with it. You can then choose the fastest that you can afford.

  Simsy 15:21 04 Oct 2007

but I'm trying to understand how the memory speed ties in with the CPU speed.

I understand your thinking with using the crucial site, but it doesn't know what cpu I'll be using.




  I am Spartacus 15:24 04 Oct 2007

I have an E6600 2.4GHz on a motherboard that has an FSB of 800/1066MHz. I also have an old benchmarking program that only recognises single core.

My Pentium 2.53GHz used to give scores around 210
The E6600 at 2.4GHz scores around 400 (single core)
The E6000 overclocked to 3.3GHz give a score of around 510 (single core)

My experience is that everything I run that uses a single core is noticeably faster than on my old system. Anything that runs using both cores simply flies. I particularly notice this in Video Editing.

PC6400 DDR2 RAM runs at 800MHz

  Simsy 15:45 04 Oct 2007

I should perhaps add that I'm not seeking to chieve some terrifically fast speed; I don't do gaming or video editing...

I'm just trying to get to understand the figures so I can get the correct match between the components.



  Simsy 05:36 05 Oct 2007

Any takers that can explain the memory speed question?




  umbongo(uk) 06:14 05 Oct 2007

memorey speeds are based on cas latency

ie the lower the latency timing the faster the ram

so a latency of 5-5-5-
will be slower than a stick with a rating of 3-3-3
heres just a few links if you want more type in google
latency explained

click here

click here

  crosstrainer 06:15 05 Oct 2007

I currently run an AMD FX cpu, on a Gigabyte mobo, with 4gb of ddr2 800 mghz. It is very much quicker with the faster ram in it, I would suggest you take this option if you can, and go for quality ram (Corsair is what I use) rather than the cheaper generic options.....You get what you pay for. Many companies offer mobo / cpu / memory bundles at very good prices indeed...Misco, Novatech to name but 2.

  Simsy 11:21 05 Oct 2007

If I use a cpu with a fsb of 800mhz I should use RAM with a speed of 800Mhz?

I assumed that to be the case... but I couldn't find any RAM at that speed. Mabe that's what I was missing!

On the assumption that such RAM , (800Mhz) is probably prohibitively expensive for me, to put my question another way, i I buy RAM with a speed of, say, 667Mhz, am I wasting money buying a processor with a fsb faster than this?

I'm still not 100% clear if these figures, (cpu fsb and RAM speed), need to match?




  I am Spartacus 11:24 05 Oct 2007

PC6400 (800MHz) RAM at click here

  crosstrainer 11:26 05 Oct 2007

I am Spatacus's link shows just how cheap ram is if you shop around...Those Corsair sticks are fine.....You only need spend more dosh if you are going to get into insane overclocking!

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