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Reunderstanding Overclocking

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May 20, 2010 8:51:24 AM

So, I feel like I might have had overclocking wrong since I thought this up, but then again I can be wrong about this. Here's my situation/thoughts:

If I have a 2.4 GHZ Q6600 (266x9), that means my FSB is at 1066 MHZ (266x4). If my RAM is DDR2 800 running at 400mhz x 2, is the RAM trying to send information faster than the FSB can handle it? In other words, would the ideal memory speed of a FSB of 1066 be DDR2 533 (266x2)? Therefore putting out just what the FSB can handle, and not backing up the RAM, allowing for lower latencies? Or am I completely wrong? :p 




Also, how does this type of situation work with I7's since they use QPI if you know. Seems a bit more confusing. I've read articles about QPI but I still don't understand what RAM speed would be pointless because it's too fast on a QPI 6.4GT/s motherboard. (or 4.8GT/s for that matter depending on the CPU)

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a b } Memory
a c 197 K Overclocking
May 20, 2010 3:25:15 PM

Sort of true.

Q6600 has an FSB frequency of 266 MHz which yields an FSB clock of 1066 MHz and a matching memory clock of 533 MHz.

If you are going to overclock, things change. Practically every G0 Q6600 will run at 3.0 GHz with little or no voltage boost. That corresponds to DDR2-667. 3.3 GHz (367 MHz X 9) corresponds to DDR2-733. Now things do not look so bad.

If you have DDR2-800 RAM, you can do one of two things. You can overclock the RAM which will get you little if anything. Or you can tighten the timing.

On my first C2 system, I had an E6600 with a mediocre cooler running at 3.3 GHz. with DDR2-1000 RAM at 5-5-5-15-2T. This was in the early days of the C2 chips and I didn't want my overclock to be limited by my memory.

Well, I worked the timing down to 3-3-3-10-1T (Orthos stable for 24 hours). I picked up a 7% increase in memory i/o. :bounce:  And discovered that that had no practical effect on overall system performance. :( 

So, yes. You can tighten the memory timing but that will accomplish only a little more than overclocking the memory would.

I am still running Core2 systems so I do not have a good feel for the QPI.

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May 20, 2010 3:54:33 PM

you do not need to worry about the speed at which your RAM runs at. running ratio of 1:1 or 1:2 is a thing of the past (Athlon XP days) this is an old myth that has been debunked a while ago. just run the CPU and ram at their fastest speed and you should be fine.
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May 20, 2010 4:42:14 PM

Okay makes sense. But one thing i want to clarify is the actual purpose of RAM frequencies/speed. If ddr2 667 is at 1:1 with my processor, for example, and it has timings of 4 4 4 12, will ddr2 800 at 4 4 4 12 be faster because of increased access times? therefore resulting in a performance boost?
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May 20, 2010 4:42:18 PM

[deleted] sorry double post.
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May 20, 2010 4:44:42 PM

phasmantis said:
Okay makes sense. But one thing i want to clarify is the actual purpose of RAM frequencies/speed. If ddr2 667 is at 1:1 with my processor, for example, and it has timings of 4 4 4 12, will ddr2 800 at 4 4 4 12 be faster because of increased access times? therefore resulting in a performance boost?


yes ddr2 @ 800 will be faster than 667 with the same timing.
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May 20, 2010 6:42:50 PM

Best answer selected by phasmantis.
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nAs an added question, would DDR2 667 with a CAS Latency of 3 be better for my computer (with a FSB of 266x4) that DDR2 800 with a CAS Latency of 4? The DDR2 667 at 3 would result in a 8.99 Nanosecond access time, where ass DDR2 800 at 4 results in a 10 Nanosecond access time. Not that I'll notice or really get any visible boost, I'm just trying to understand how RAM works more.
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