What is the impact of memory Voltage rating

rimmi2002

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Sep 17, 2007
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Hi i am looking for new memory and had a question what impact does the voltage rating have on thec compatability and overclocking ability of a memory chip. Seems like voltage ranges from 1.8 to 2.2 or so. Which area is it better to get the memory in. thanks.
 

Mondoman

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Jan 4, 2008
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Above the standard 1.8-1.9V means the module couldn't run at the given speed/timings at the standard DDR2 voltage, so they boosted the voltage to get it to run at the desired speed (this is factory-sanctioned overclocking). If the factory had to overclock the RAM just to get it to the spec they're selling it at, there's likely to be less room left for further overclocking. Some manufacturers seem to concentrate so much on factory-sanctioned overclocks that their modules aren't as compatible under standard DDR2 conditions (e.g. OCZ).
Thus, the best quality modules will run a given DDR2 spec at 1.8V.
Note that this is not the same as saying that all modules advertised at 1.8V are the best quality.
 

Idontcare

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Oct 10, 1999
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Originally posted by: Mondoman
Above the standard 1.8-1.9V means the module couldn't run at the given speed/timings at the standard DDR2 voltage, so they boosted the voltage to get it to run at the desired speed (this is factory-sanctioned overclocking). If the factory had to overclock the RAM just to get it to the spec they're selling it at, there's likely to be less room left for further overclocking. Some manufacturers seem to concentrate so much on factory-sanctioned overclocks that their modules aren't as compatible under standard DDR2 conditions (e.g. OCZ).

Is it really fair to call it overclocking if it is rated to operate at those volts and those timings by whomever manufactured the DIMM?

You don't call it "factory sanctioned overclocking" when you drive your automobile faster than the state specified speed-limits...do you?

Just because Jedec specified the speed limit (DDR2-800 and 1.8V) does not mean that operating the ram above this limit means it is overclocked.

Overclocking is strictly a term intended to reference the actions of the end-user when the end-user is operating the ram beyond the manufacturers specified speed, voltages and timings.
 

Mondoman

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Jan 4, 2008
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Originally posted by: Idontcare
...
Is it really fair to call it overclocking if it is rated to operate at those volts and those timings by whomever manufactured the DIMM?
Yes, because the RAM is being overclocked vs. the DDR2 standard. If the manufacturer comes up with their own DDRx standard that accomodates such voltages, then they can sell it as DDRx (not DDR2) and it would not be considered overclocked.

You don't call it "factory sanctioned overclocking" when you drive your automobile faster than the state specified speed-limits...do you?
That's because the state didn't design/make the car. However, when you reflash the ECU of a car so that it operates outside the design boundaries, the car is considered "modded" (car version of "overclocked").

Just because Jedec specified ... 1.8V) does not mean that operating the ram above this limit means it is overclocked.
Sure it does, if it is being sold as "DDR2 RAM". If instead it is sold as DDRx RAM (see above), that would not be overclocking.

Overclocking is strictly a term intended to reference the actions of the end-user when the end-user is operating the ram beyond the manufacturers specified speed, voltages and timings.
Sorry, no. For example, look at the number of factory-sanctioned graphics chip overclocks on graphics boards.


 

rimmi2002

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Sep 17, 2007
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I am kinda overwhelmed on how to make a decision based on this information, becausethis means memory with higher CAS latency (5) and low voltage (1.8) can have some unknown potention for overclocking vs. a memory with low CAS latency (4) and high voltage (2.1 - 2.2) is already maxed out and I might have to lower setting to overclock my computer....so can you please help me out.

I am looking to buy an e2180 or e4xxx or maybe e6550 and overclock it. Which of the following memories with be the fastest and gives me the most overclocking headroom?


1. CORSAIR XMS2 2GB (2 x 1GB)
Timings 4-4-4-12
Voltage 2.1V

2. G.SKILL 2GB (2 x 1GB)
Timing - 5-5-5-15
Voltage - 1.8V - 2.0V

3. Crucial Ballistix 2GB
Timing - 4-4-4-12
Voltage - 2.2V

4. A-DATA 2GB (2 x 1GB)
Timing - 5-5-5-18
Voltage - 1.8V

Thanks.
 

Mondoman

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Jan 4, 2008
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None of those; I'd go with these Corsair: http://www.newegg.com/Product/...x?Item=N82E16820145590 ($34 after rebate, with free shipping to boot).
Remember, OCing RAM on its own does very little to boost performance; they key is just to have RAM fast enough to keep up with the CPU overclock (i.e. the FSB). Current motherboards support 1333MHz FSB, and some support 1600MHz FSB. DDR2-800 is the correct speed for 1600MHz FSB, so it's unlikely you will need RAM faster than that.
The e2xxx and e4xxx are designed to run on an 800MHz FSB, so running on a 1600MHz FSB is a 2x overclock, which should be plenty (if the CPU core even supports that speed). Certainly no need for RAM faster than DDR2-800 for these.
The e6550 is designed for 1333MHz FSB, so running it at 1600MHz gives only a 20% overclock. Overclocking it further should be possible, but will require running RAM faster than DDR2-800, so overclocking the RAM or using faster RAM would be needed here.
IMHO, since an e6xxx or e8xxx CPU costs more than an e2xxx or e4xxx and requires much more expensive RAM for a substantial OC, your best bet is an e2xxx or e4xxx.
 

rimmi2002

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Sep 17, 2007
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yeah I am looking at the E2xxx or E4xxx. Since both are 800mhz FSB, are both just as over clockable?...because in that case I would prefer the E4xxx if I get a good deal on it because of the extra 1mb of cache.

Also as for memory I know that e6xxx or e8xxxx have less overhead for overclocking because they having higher FSB, but people have been able to overclock then well also, by pushing memory over 400mhz.. what I was wondering if I were in that situation where I end up running the FSB at 450 (450x4 = 1800) and am pushing the memory more the recc'd bus on it...which memory of the ones I listed above would be more like to be stable in such a situation. thanks.
 

Mondoman

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Jan 4, 2008
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If you want to go faster than DDR2-800 best bet is to get actual DDR2-1066 RAM, or at least DDR2-800 RAM that is rated at 4-4-4 at 1.8/1.9V. None of the 4 you list meet that spec.
The reasoning is that timings are listed in terms of clock cycles, which get shorter at higher speeds, while actual chip performance is a fixed amount of time. Thus, to a first approximation, being rated at 4-4-4 at DDR2-800 speed is the same as being rated at 5-5-5 at DDR2-1000 speed.