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Memory - speed vs overclock

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May 14, 2012 4:37:15 AM

I'm putting together a system with the Asus Rampage Extreme IV board. (CPU i7-3930K) The specs say this for supported memory:

"DDR3 2400(O.C.)/2133(O.C.)/1866/1600/1333/1066 MHz Non-ECC"

I'm a little confused on what to buy. Should I buy 1866 RAM, and when I overclock, it will perform at higher speeds (like 2400)? Or are they saying that in order to have the memory keep up with the computer when overclocking, I need to buy faster RAM (2400)?

Does that question make sense? Obviously there is a price premium for the faster stuff. Would love it if someone could explain this to me and help me make the right decision...

Thanks!
Mike

More about : memory speed overclock

a b } Memory
a b K Overclocking
May 14, 2012 7:31:53 AM

O.C, next to the RAM frequency specifications, tells us that the RAM isn't automatically supported at that speed, but it is supported and you must manually overclock the RAM it to get those speeds. Basically, you can buy a 2133MHz memory kit, but you need to set it to that frequency yourself in the BIOS, or else it will default to a lower frequency.

Basically, the board supports overclocking your RAM to those speeds, if you want to. Buying an 1866MHz kit and putting it in will not make a difference, it will still be 1866MHz (unless you overclock it further). You don't need to buy faster RAM, it's just telling you that it can support those speeds, but it doesn't automatically recognize RAM at those speeds.
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May 14, 2012 12:55:24 PM

Cool... so if I'm understanding correctly, there's no advantage to me buying 2400mHz memory over 1866mHz memory:

- 1866mHz memory would recognize at 1866 by default
- 2400mHz memory would recognize at 1866, as the highest (non-overclock) speed supported

I'm still going to have to overclock it either way from the default max speed of 1866mHz to 2400. But is it easier on the RAM chips if they have a higher clock speed to start with? In other words, is it better to use 2400mHz memory and I OC the rate from 1866 to 2400, versus using 1866 RAM and overclocking that?

Thanks!!
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a b } Memory
May 14, 2012 1:45:24 PM

well for future 2400mhz is good than 1866mhz
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a b } Memory
May 14, 2012 1:49:16 PM

and i have little doubt that 1866 will run at its own speed cause i7 support 1333-1600mhz so i think you need to made some changes to use 1866mhz otherwise it'll downgrade its clock speed
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a b } Memory
a b K Overclocking
May 14, 2012 2:34:01 PM

The CPU does not choose what the memory is recognized, the motherboard does. The CPUs will run at whatever the motherboard tells them too. They just don't officially support more than 1333MHz because when they first came out, that was really the best that was commonly available and Intel didn't care to change the specs. The Intel CPUs will support pretty much any frequency that you throw at them, albeit you need to keep the voltages in check.

Yes, it is better to use 2400MHz RAM at 2400MHz than to use 1866MHz RAM at 2400MHz. The RAM is rated for it's speed because that is what it was intended to be run at, so that is what it is designed and binned to run at. 1866MHz memory at 2400MHz would require a big voltage hike, probably enough to shorten the life time of that CPU significantly, unless you got your hands on a very good kit.

Really, there's no reason to run at 2400MHz anyway. It won't help anything other than rendering and archiving too much (gaming is notorious for not taking good advantage of faster RAM) anyway, so it's not worth the risk, let alone the cost of such high performance memory. It's also good for things such as AES performance (on CPUs that have hardware AES acceleration, such as Sandy and Ivy Bridge i5s and i7s, plus Bulldozer FXs (and the Xeon and Opteron counterparts to these CPUs).

I recommend against buying anything rated higher than 1866MHz because as cost goes up, the performance improvement doesn't really improve much at all.
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a b } Memory
May 14, 2012 2:49:39 PM

imo cpu does cause now days memory controllers located inside processor
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May 14, 2012 3:04:10 PM

Quote:
Yes, it is better to use 2400MHz RAM at 2400MHz than to use 1866MHz RAM at 2400MHz. The RAM is rated for it's speed because that is what it was intended to be run at, so that is what it is designed and binned to run at. 1866MHz memory at 2400MHz would require a big voltage hike, probably enough to shorten the life time of that CPU significantly, unless you got your hands on a very good kit.

Really, there's no reason to run at 2400MHz anyway. It won't help anything other than rendering and archiving too much (gaming is notorious for not taking good advantage of faster RAM) anyway, so it's not worth the risk, let alone the cost of such high performance memory. It's also good for things such as AES performance (on CPUs that have hardware AES acceleration, such as Sandy and Ivy Bridge i5s and i7s, plus Bulldozer FXs (and the Xeon and Opteron counterparts to these CPUs).

I recommend against buying anything rated higher than 1866MHz because as cost goes up, the performance improvement doesn't really improve much at all.
Perfect explanation.
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May 14, 2012 3:06:15 PM

when i was messing with ddr2 ram on an AMD 955 ... 800ddr2 44412 seemed to be the same speed as 1066 55515... using 1t does speed up memory benchmarks...
overclocking RAM tend to score higher on benchmarks... 1866ddr3 9 10 9 27 is the same speed as 1600ddr3 88824 (and the 1600 speed is probably more stable.)
i know while i can get 1866 9 10 9 27 to work on my 1100t, it is not faster on the crysis cpu1 benchmark compared to 1600 888 24... so while it is faster on memory benchmarks the reality is that tends to make no difference... i went with stability over "super specs"

if memory speed makes a diffence the program is badly written.. because the CPU's caches are alot faster than the memory...
thus YMMV...

to answer your question get the one you can afford.
have you noticed that memory specs tend to have the memory speed divided by the latency equals 200?
1333 77721 = 190.4286
1600 88824 = 200; 1600 99927 = 177.7778
1866 9 10 9 27 = 207.3333 (as corsair memory it is expensive... 80 for 8GB! but i can run it at 1600 88824, prime95 stable for at least 42 hours.)

so you you will find that generally expensive RAM tends to be faster. but remember:

You get what you pay for if you know what you are doing, otherwise you get what you deserve.
simplest thing to so is look up the qualified memory for your motherboard, and get the fastest ram listed (keeping in mind the latency if it)
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a b } Memory
a b K Overclocking
May 14, 2012 3:46:14 PM

redeye said:
when i was messing with ddr2 ram on an AMD 955 ... 800ddr2 44412 seemed to be the same speed as 1066 55515... using 1t does speed up memory benchmarks...
overclocking RAM tend to score higher on benchmarks... 1866ddr3 9 10 9 27 is the same speed as 1600ddr3 88824 (and the 1600 speed is probably more stable.)
i know while i can get 1866 9 10 9 27 to work on my 1100t, it is not faster on the crysis cpu1 benchmark compared to 1600 888 24... so while it is faster on memory benchmarks the reality is that tends to make no difference... i went with stability over "super specs"

if memory speed makes a diffence the program is badly written.. because the CPU's caches are alot faster than the memory...
thus YMMV...

to answer your question get the one you can afford.
have you noticed that memory specs tend to have the memory speed divided by the latency equals 200?
1333 77721 = 190.4286
1600 88824 = 200; 1600 99927 = 177.7778
1866 9 10 9 27 = 207.3333 (as corsair memory it is expensive... 80 for 8GB! but i can run it at 1600 88824, prime95 stable for at least 42 hours.)

so you you will find that generally expensive RAM tends to be faster. but remember:

You get what you pay for if you know what you are doing, otherwise you get what you deserve.
simplest thing to so is look up the qualified memory for your motherboard, and get the fastest ram listed (keeping in mind the latency if it)


Some types of programs need too much data for the cache to keep up, so they are reliant on memory performance. For example, a lot of folding-style workloads are just too much for the cache to keep up with because they use too much data too few times. Basically, anything like rendering, archiving, folding, or really any other similar number crunching workload can be very RAM bandwidth and sometimes also RAM latency dependent. It's not always about how poorly coded something is, it's also about what it is. What type of RAM optimization (low latency, high bandwidth, balance of both) helps the most simply depends on the program. Most modern programs that are used by consumers are not RAM dependent and like you said, are generally only RAM dependant these days if they are poorly coded. However, like I said, that is not true for all programs.
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a b } Memory
a b K Overclocking
May 14, 2012 3:48:34 PM

THE UNKNOWN said:
imo cpu does cause now days memory controllers located inside processor


The controller is on-board the CPU, but the BIOS is still in control of the memory performance. You can run over 3GHz DDR3 on Intel's Sandy Bridge CPUs (given the right motherboard, memory, and cooling) if you wanted to (some people have done it, usually overclocking record seekers). The BIOS is on a chip on the motherboard, so the motherboard controls the memory frequency (in that sense, because you use the BIOS to control the CPU's many functions).
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a b } Memory
May 14, 2012 4:15:16 PM

But that's called oc
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a b } Memory
a b K Overclocking
May 14, 2012 4:19:53 PM

THE UNKNOWN said:
But that's called oc


Regardless, it is the motherboard that chooses what memory can default to. If a motherboard's specifications do not state that a frequency for memory is OC only, then it can almost assuredly default memory to that speed. For example, this motherboard can probably default memory to 1866MHz. Most motherboards can default memory to at least 1600MHz.
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a b } Memory
May 14, 2012 4:24:15 PM

yes but question is i7 memory frequency says 1600mhz
anything above will oc
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a b } Memory
a b K Overclocking
May 14, 2012 4:45:48 PM

THE UNKNOWN said:
yes but question is i7 memory frequency says 1600mhz
anything above will oc


No. This motherboard supports native frequencies up to 1866MHz. The CPU does not decide what is an overclock and what is not, the motherboard decides. If the motherboard supported native frequencies up to 2400MHz, then even up to 2400MHz could be a native frequency and not an overclock (unless you were using RAM that is not rated for 2400MHz and you overclocked it to 2400MHz, but that's beside the point). The CPU's memory specifications really aren't very important, overall, just a guideline for the highest common frequency of the time when the processor is launched.
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a b } Memory
May 14, 2012 4:56:28 PM

yes your right but question is intel officially supports 1333-1600mhz you can force bios to reach 1866mhz and mobo is also supported 1866 without oc but in that matter memory controller are inside of the processor as intel says 1600mhz stock
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a b } Memory
a b K Overclocking
May 14, 2012 5:23:46 PM

THE UNKNOWN said:
yes your right but question is intel officially supports 1333-1600mhz you can force bios to reach 1866mhz and mobo is also supported 1866 without oc but in that matter memory controller are inside of the processor as intel says 1600mhz stock


Intel doesn't say 1600MHz is stock, they recommend 1600MHz as stock. The board decides what is or isn't stock. Where the memory controller is does not matter because it is not the deciding factor in this with the i5s and i7s.
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May 14, 2012 6:20:26 PM

I went ahead and bought the 2400mHz RAM.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Thanks everyone for the info. I understand that the RAM will not exceed 1866mHz until I overclock it in the BIOS, at which time I should be able to get it to run at 2400mHz. Or perhaps it will burn up to a crisp, I'm not sure... my luck hasn't been with me today... :) 

Rush processing, overnight shipping, should have it tomorrow! Thanks for the help, I'm good here... (I think)

Mike
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a b } Memory
a b K Overclocking
May 14, 2012 6:22:12 PM

All right then, I guess it's case closed for this thread once you get the memory and get it working. You're welcome.
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a b } Memory
May 14, 2012 6:24:10 PM

No problem :) 
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May 29, 2012 1:17:44 PM

Best answer selected by mick_nyc.
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a c 146 } Memory
a b K Overclocking
May 30, 2012 11:35:11 AM

This topic has been closed by Nikorr
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