Q6600 need 1066MHz RAM?

Benjamonous

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I'm a n00b when it comes to this, but I'm trying to understand what the best RAM is to build a new system that has Intel's Quad-Core Q6600 with a FSB of 1066MHz.

In order to get the maximum performance, does that mean I need to buy RAM with a clock speed of 1066MHz to match the CPU's FSB?

Or does Dual-Channel only require RAM with 533MHz, and then it doubles it?

I want to make sure to eliminate as many bottlenecks as I can.

Thanks in advance!
 

jackluo923

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Both the 1066mhz single channel and 533mhz dual channel options works. But 1066mhz memory are a lot more expensive than dual channel 533mhz. If you have a lot of budget and want a maximum performance, get 1066mhz, if not, get 667mhz memory sticks because its cheaper than 533mhz ones.
 
for stock (non overclocking) dual channel DDR2-533 is sufficent (2x533=1066 total bandwidth to match the 1066mhz fsb or 1:1 result), but since 667 is the new standard go for some 667 spec ram ;)
 

jackluo923

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The pro of buying 667mhz DDR2 is its cheap price and its ability to down clock to 533mhz and tighten the timing or overclock to 800mhz and loosen some timing.
 

jackluo923

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Here in Canada, the price is like this
2x1gb ddr2 533 cl3 is around 70$
2x1gb ddr2 667 cl4 is around 60$
2x1gb ddr2 800 cl4 is around 100$
2x1gb ddr2 800 cl5 is around 95$

So if you live where i live, its clearly that 667mhz is a better buy since its 35-40% increase in price and only 20%.
You can easily overclock 667mhz cl4 to 800mhz cl5. All you need is to adjust the frequency and up the voltage to 2.1v or around that.
 

Benjamonous

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Thanks for all the input, guys!

So, if I'm understanding this correctly, you're saying it's better to buy a higher clocked RAM, e.g., 800MHz, and then down-clock it to 533MHz to synchronize it with the FSB?

Why is that better? What are the advantages of that over just buying some 533MHz RAM? (Again, forgive my n00bosity!)


Thanks
 

jackluo923

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I used to think its better to downclock the 800mhz ddr2 to 533mhz until mondoman corrected my mistake. The advantages of getting 667mhz is the price/performance since you can overclock it to 800mhz level. And 800mhz 's performance is better than 533mhz ones.
 

IcY18

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for stock (non overclocking) dual channel DDR2-533 is sufficent (2x533=1066 total bandwidth to match the 1066mhz fsb or 1:1 result), but since 667 is the new standard go for some 667 spec ram ;)

Just for clarification purposes

Not sure how you get 533x2 = 1066 which matches a 1:1. I and maybe you fully understand the concept behind a 1:1 ratio between the fsb and memory but how you demonstrated so is even more confusing since the op didn't have a full understanding of ddr2 memory and its effective speed.

Just clarify memory and fsb run on the same internal clock, that is 266mhz in this instance. The fsb is quad pumped so it equals an effective rate of 1066mhz and memory is DDR, DOUBLE data rate, which equals 533 mhz. For the cpu you take the appropiate multiplier and multiply it by the internal clock 266.

At these speeds your cpu and memory run at a 1:1 ratio

@ the OP...

There is no advantage to buying more expensive ram like ddr2-800 and then clock it down to ddr2-533. If you think you will just leave this computer like it is with no overclocking now or in the future then just get ddr2-533 with low timings.

If you have some extra cash that you can spend on memory then you could either opt for ddr2-800 or ddr2-1066, if your going for it you might as well go for it and just get ddr2-1066 and run you ram at a 1:2 ratio. which would be easy and simple.

lastly just note that the performance improvements beyond ddr2-533 won't be big enough to really blow you away unless you benchmarking it.
 

Mondoman

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Just clarify memory and fsb run on the same internal clock, that is 266mhz in this instance. ...
No, on current Intel CPUs the memory bus is separate from the FSB and each has its own clock. Thus, one can run a stock 266MHz FSB clock while varying the memory bus clock to run (e.g.) DDR2-800 speed RAM.

As for the 1:1 ratio, what they're trying to match is the max data rates of the two buses. If the FSB has a 1066MHz data rate, that's equal to memory running in dual-channel mode (d-c mode doubles the data rate) at DDR2-533 speed.
 

Benjamonous

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So, I'm still confused as to why DDR2-800 would be better to use than DDR2-533.

What's the benefit? Isn't it more important to have the RAM synced with the CPU FSB? If so, why is 800MHz better than 533MHz?

Thanks again!
 

IcY18

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...

Just clarify memory and fsb run on the same internal clock, that is 266mhz in this instance. ...
No, on current Intel CPUs the memory bus is separate from the FSB and each has its own clock. Thus, one can run a stock 266MHz FSB clock while varying the memory bus clock to run (e.g.) DDR2-800 speed RAM.


That is exactly what i said...and yes they do both run on the same internal clock unless you specify with a different ratio. I know they both have a separate clock but with out applying any multipliers or ratios you have to begin with 266.

@benj

Typically its always smarter to leave your memory and cpu at a 1:1 ratio. But if you don't plan on overclocking your processor but you have ram that has a higher speed of ddr2-667(assuming your cpu has an fsb of 266) then you can run it at higher speeds and see performance increase. Its also beneficial to run it at 1:1 when overclocking cause you can get a higher stable overclock
 

Benjamonous

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So, I'm still confused as to why DDR2-800 would be better to use than DDR2-533.
Because it will be faster. Not by a lot, but it will be faster.

Haha, yeah sorry, that does sound pretty stupid. Let me clarify...

I thought you were saying it'd be better to buy DDR2-800 RAM and down-clock it to 533MHz to match the CPU FSB when it goes Dual Channel.

My question is, why would the "800MHz --> 533MHz" RAM be any better than just getting normal "533MHz" RAM?

If they both have the same clock speed, shouldn't they perform the same?

I'm just trying to gain enlightenment, that's all.

Thanks!
 

jackluo923

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Because it will be faster. Not by a lot, but it will be faster.

he meant by getting 800mhz memory and run it at 800mhz. Not downclock it to 533mhz. You'll need to adjust your Ram divider if you're going to do this.
 

IcY18

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...and yes they do both run on the same internal clock ...
...they both have a separate clock
You can see why we might get confused here... :wink:

Its also beneficial to run it at 1:1 when overclocking cause you can get a higher stable overclock
Interesting, I hadn't heard that before. Do you have any links to tests/data on this?

Well that separate quote means nothing since you left out the more important part of it "they have a separate clock after applying multipliers and ratios.

As far as the overclocking at a 1:1 how many sites now a days do you see unlinking the memory and why is everyone including yourself recommending higher performance memory if we all could just run certain dividers while still achieving the same higher clockspeed with cheaper memory...

its just accepted practice that you will always be more stable when your memory and cpu are linked.
 

jackluo923

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how many sites now a days do you see unlinking the memory and why is everyone including yourself recommending higher performance memory if we all could just run certain dividers while still achieving the same higher clockspeed with cheaper memory...

He is suggesting to buy the 800mhz ram if he wanted to run in unlinked. It does outperform 553mhz in dual channel in 1:1 ratio in all of the benchmarks quite a bit.

Here's the link Mondoman gave above http://www.madshrimps.be/?action=getarticle&number=1&artpage=1...&ar

please read it and you'll understand.


its just accepted practice that you will always be more stable when your memory and cpu are linked.

That is not always true. It's only true when you have poor quality motherboard where higher speed of Ram will cause the Northbridge or the IMC in AMD's case unstable. If you have good overclocking motherboard such as Asus P5B delux with P965 chipset, you won't lose stability when you set the memory and cpu unlinked. In fact, you might achieve better stability using unlinked memory where you downclock the memory speed for the cost of less performance.
 

IcY18

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that section of my post about the memory only applied to overclocking, not running the memory at higher speeds at a different ratio.

And no downclocking your memory running different dividers will not increase stability if your ram is capable, that is why every extreme overclocker buys high performance memory cause they need to run them at a 1:1 ratio to get a higher stable overclock.

Concerning the performance of ddr2-800(with pretty tight timings) over ddr2-533 in most cases you'll net an increase in 5 fps in most games. At this time ddr2 is dirt cheap so thats all fine and dandy but only 5 months ago ddr2 prices were sky rocketed so buying ddr2-800 if you weren't going to overclock was costing you enough money that you could have just bought a better video card.
 

Mondoman

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its just accepted practice that you will always be more stable when your memory and cpu are linked.
Bloodletting was an accepted practice for hundreds of years to "cure" many ailments. :wink:
Until just recently, using stents as scaffolds to hold open arteries after angioplasties was an accepted practice to prevent future deaths by heart attack.
Testing and data are very helpful. Failing that, a reasonable theory is nice (but might be wrong, as with the stents).

I'm not saying that syncing the memory and FSB buses won't help stability, I'm just saying that it's not clear to me why that would be, and I'm curious if there's any actual data saying that it is.
 

tsf

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if i were u, i would go for a ddr2-800 and then overclock the processor a bit to get 1:1 ratio. its not overclockin much and shouldn't be much problem with a Q6600 with stock cooler.a bit better performance for $10 extra.

i'm saying this based on my knowledge of an E6420. correct me if i'm wrong.
 

tsf

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if i were u, i would go for a ddr2-800 and then overclock the processor a bit to get 1:1 ratio. its not overclockin much and shouldn't be much problem with a Q6600 with stock cooler.a bit better performance for $10 extra.

i'm saying this based on my knowledge of an E6420. correct me if i'm wrong.
 

IcY18

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If he overclocks his cpu at a 1:1 ratio to a 400fsb then he will be clocked at 3.6ghz, unfortunately Intel isn't that generous in their stock coolers. Even high end aircooling would have a very hard time getting to that range. With the stock cooler he'd be lucky to get to 2.6-2.8ghz.
 

tsf

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oops! haven't thought of that! maybe ddr2-667 isn't such a bad idea, even for a e6420 (400x8=3.2ghz! no thnx!!)