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Memory Overclock Clarification and Advice- Guide Question

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October 21, 2006 3:40:48 AM

I'm reading through the Core 2 Overclocking guide very carefully as this is all brand new to me. I've been through it a number of times and one thing just doesnt click for me with the memory portion.I will have a AsusP5BDeluxe but I want to understand the timing issue mentioned on the bottem here regarding setting Timing: 5-5-5-15 vDIMM: 2.2V when 1FSB:1RAM is overclocked above the rated frequency. I'm missing something that helps me recognize when exactly this is the case. Could someone please clarify this? I'm deciding between Corsair ddr2-675 or ddr2-800, both with 4-4-4-12 timing. Would either of these be cases to switch the timing to 5-5-5-15 based on what the guide is advising? I'm somehow missing the connection with the example at the bottem of when to do so. I'm simply trying to clearly see what connection I'm missing with the concept of 1FSB:1RAM. And finally, which is a better choice of memory(the ddr2-800 is $70 more) in this instance including cost factor(it's for a 6400 or 6600)? Thanks in advance

Parts From Guide:

ASUS: Set ‘DRAM Frequency’ to DDR2-533 @266Mhz FSB (1FSB:1RAM operation)
As you increase the FSB, the RAM will follow in the pattern of 1:1 shown in BIOS.

1. Set ‘DRAM Timing’ to manual or disable SPD (use SPD for P5W DH)
2. In BIOS you will see 4 separate timing digits, change them to the ones specified on your RAM

When 1FSB:1RAM is overclocked above the rated frequency of your RAM use the following values
Timing: 5-5-5-15
vDIMM: 2.2V

e.g. DDR2-667 4-4-4-12 1.9V operating at ~400Mhz will need to be set to 5-5-5-15 2.2V
October 21, 2006 3:25:26 PM

I think you mean 667 RAM, not 675?? In any case.......

4-x-x-x timings are better, but it's the 667 or 800 that's more important in this case. The reason is simple (I'll try to explain it like somone explained to me cuz I didn't understand at first either):

If you want to overclock and get best possible performance, generally speaking, you keep the timings low (CL4) and 1:1 FSB-RAM. Then you raise your FSB up, tweak the volts if necessary, etc. The issue here is this:

The 667 RAM will top out sooner than the 800 because it can't go as high. So then you loosen the timings from 4-x-x-x to 5-x-x-x. That lets you go higher on your FSB. But there is some performance hit...if you can go high enough with the FSB, that will compensate, and you will get your performance back. They key here is that keep 1:1 minimizes the performance hit because if you have to change the ratio then you're sacrificing performance for high clocks, and in the end you're no better off. HOWEVER, the 800 RAM can go much higher at 1:1. So you can raise your FSB higher, while keeping the timings at 4-x-x-x. You won't need to go to 5-x-x-x. And if/when you do, it's the same conundrum as I just described, except that you're way higher on the FSB already.

So, getting a good overclock out of 667 RAM means you'll have to loosen the timings to 5-x-x-x anyways, so that 4-x-x-x RAM (and the extra $$ you paid is a waste) won't go nearly as high as 800 RAM, even if it's 5-x-x-x.

So, in a nutshell, if you want a decent overclock, go with 800 @ 4-x-x-x if at all possible. It will let you get a very respectable overclock while keeping the CL4 timings. If you want an insane overclock, just go with the 5-x-x-x (800) RAM because you'll have to go to those timings anyway.


I sure hope that made sense. In one line:

If you want a good OC, get 800 RAM, CL4 if possible; but if it's too much money then just go with the CL5 stuff and you'll do fine.


Good luck.
October 21, 2006 9:44:45 PM

Quote:
ASUS: Set ‘DRAM Frequency’ to DDR2-533 @266Mhz FSB (1FSB:1RAM operation)
As you increase the FSB, the RAM will follow in the pattern of 1:1 shown in BIOS.

1. Set ‘DRAM Timing’ to manual or disable SPD (use SPD for P5W DH)
2. In BIOS you will see 4 separate timing digits, change them to the ones specified on your RAM

When 1FSB:1RAM is overclocked above the rated frequency of your RAM use the following values
Timing: 5-5-5-15
vDIMM: 2.2V

e.g. DDR2-667 4-4-4-12 1.9V operating at ~400Mhz will need to be set to 5-5-5-15 2.2V


When auto-overclocking, the auto config of the mobo might loosen timing to 5-5-5-15, but you can control them manually and tighten if the memory will handle it...
Again, go for the DDR2-800 at the lowest timings you can afford...
October 22, 2006 2:23:01 AM

Quote:
Without any info on which CPU you're going to use, any infi I give you will be useless.

[EDITED]
And finally, which is a better choice of memory(the ddr2-800 is $70 more) in this instance including cost factor(it's for a 6400 or 6600)? Thanks in advance

If you were to weight between 675+E6600 vs. 800+E6400, the clear option is the first one. Performance/$ and maximum CPU Mhz wise.
The exact reason behind it is a complicated one.


I appreciate the advice. Unfortunately not knowing which CPU I'm going to use is part of the equation right now for me. Thanks
!