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Memory voltage ?

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January 17, 2010 5:40:17 PM

Does lower voltage equal less performance? Im looking at some memory for a new build.

G.SKILL ECO Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL8D-4GBECO - Retail


or this

CORSAIR XMS3 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) ... - Retail

thanks

More about : memory voltage

a b } Memory
January 17, 2010 5:57:11 PM

What chip are you pairing this RAM with?

To answer your question: No. In fact it's possible that lower voltage could be better performing because lower voltage should equate to better (i.e. lower) heat.

Both RAMs have the same frequency. I can tell from the model number of the G.Skill that it is CL 8. What is the CL rating of the Corsair? If it is lower than 8 then it should perform better than the G.Skills, if it is 8 than the same, if it is higher than worse. Of course that is all theoretical and real performance depends on how they actually function once inserted in your motherboard. Also, there is little real world difference between small steps up in RAM.


If you're up for some reading, you may find the following articles interesting if you haven't seen them already. However, they are about performance:

http://www.tomshardware.com/reviews/memory-scaling-i7,2...
http://www.anandtech.com/memory/showdoc.aspx?i=3589

Both of those articles were written about the i7 9xx / 1366 socket chips. I haven't kept track of any articles on RAM speeds tested on AMD but could probably dig one up. I also haven't seen a lot of articles specifically focused on RAM speeds on the newer P55 platform. However, Tom's has had two.

First up: http://www.tomshardware.com/reviews/core-i7-870-1156,24...
I didn't care for the way results are presented, to me it's not as clear cut as it could have been. I think it points out there's little difference between marginally slower and faster RAM but the way the results are shown leave room for individual interpretation. Also in the opening they say testing was done with an i7 860 but the test page (and the URL) states that they used an 870. Still worth a read.

And finally, they did a review of value RAM you may also find interesting: http://www.tomshardware.com/reviews/ddr3-4gb-p55,2462.h...
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January 17, 2010 6:05:40 PM

the corsair is 8 as well, here is the mb im thinking about using

ASRock P55M Pro LGA 1156 Intel P55 Micro ATX Intel Motherboard - Retail


would this be ok for a mid range gaming system?
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a b } Memory
January 17, 2010 6:20:39 PM

Which CPU are you using? The i5 750?

This should be fine for mid-range gaming. Your GPU selection is going to have the biggest impact on your gaming experience.
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January 17, 2010 6:40:42 PM

i am using the i5-750

thanks for your help
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a b } Memory
January 17, 2010 7:09:44 PM

slick2010 said:
i am using the i5-750

Ok, the reason I asked about your CPU is I wanted to make sure you knew that you cannot natively run RAM at 1600 MHz when paired with an i5 750. A lot of people buy 1600 MHz RAM and are then disappointed when there is not an easy setting to flip that will make the RAM operate at 1600 MHz. You will often see suggestions to turn on XMP which will let your RAM run at 1600 MHz, but there are side effects that are usually not mentioned.

There can still be some advantages to getting 1600 RAM. For example, if you're going to overclock it can give you more headroom. Also, every once in a while you can find 1600 RAM with equal or lower CAS ratings for the same or cheaper price.

The long explanation I usually provide is as follows:

With an i5 750 you cannot run RAM any faster than 1333 with effectively OCing your computer. You can often turn on XMP in BIOS, and many people recommend doing this, but this changes your BCLK which also affects your CPU speed. It might, as a side effect, end up turning off functionality such as Turbo, EIST, sleep states. You can usually turn those back on but you have to specifically do it. This differs from motherboard to motherboard.

To provide a little more detail on why memory multipliers and XMP affect your CPU, we need to discuss how the RAM and CPU speeds are determined. There are 3 important settings: BCLK, Memory Multiplier, and the CPU Clock Ratio.

RAM Speed = BCLK x Memory Multiplier
CPU Speed = BCLK x CPU Clock Ratio

By default, the 1156 socket chips run with a BCLK of 133. The CPU and RAM attain different speeds by using different multipliers.

The Max Memory Multiplier that is available to the i5 750 chip is one that allows RAM to reach a speed of 1333 MHz at default BCLK. Doing the math, this is basically 10 (some boards treat it differently, but fundamentally it can be thought of as 10) because 133 BCLK x 10 Memory Multiplier = 1333 MHz.

The Max Memory Multiplier that is available to the i7 8xx chips is one that allows RAM to reach a speed of 1600 MHz at default BCLK. Doing the math, this is essentially 12 because 133 BCLK x 12 Memory Multiplier = 1600 MHz.

The i5 750 runs with a default CPU Clock Ratio of 20. This gives it it's default CPU speed of 133 BCLK x 20 CPU Clock Ratio = 2.66 GHz. When XMP is turned on for 1600 MHz RAM, the BCLK is usually changed to 160 (this could differ between boards as well). Remember, the max memory multiplier available to the i5 750 is 10, so to hit 1600 MHz the motherboard must change the BCLK to: 1600 / 10 = 160.

As a result of this BCLK change, the CPU speed changes. If the CPU Clock Ratio did not change your CPU would be OCed to 20 x 160 = 3.2 GHz. Most (if not all) motherboards would deem this too dangerous to allow when a user only flips the XMP profile. So, the boards drop the CPU Clock Ratio in response to the raised BCLK. Based on what I've seen around the forum, most boards will drop the CPU Clock Ratio to 17. This means your CPU is running at a speed of 17 * 160 = 2.72 GHz.

I don't know how other motherboards handle this, but Gigabyte treats this as an OC. If you have left other settings as is, they will disable Turbo, EIST, and Sleep States. These functions can be turned back on, but you have to go in and flip the settings from "Auto" to "Enabled". "Auto" means the motherboard decides whether or not to allow these functions. By setting it to "enabled" you ensure that they are always available.

Of course once you have XMP turned on and your BLCK gets bumped up to 160, Turbo will run your machine even faster. When Turbo kicks in, the CPU Clock Ratio changes. For example, with one core of an i5 750 active Turbo might raise the CPU Clock Ratio as high 24. This gives a stock CPU a max speed of 133 BCLK x 24 CPU Clock Ratio = 3.20 GHz. But with XMP on and a BCLK of 160, your new max speed is 160 x 24 = 3.84 GHz (assuming turbo raises the multiplier this high**). You'll want to test your system for stability running at these settings. Keep an eye on Voltage and heat.


Putting this all together, at default/stock we have:
BCLK = 133
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 20

RAM Speed = BCLK x Memory Multiplier = 133 x 10 = 1333 MHz
CPU Speed = BCLK x CPU Clock Ratio = 133 x 20 = 2.66 GHz

When Turbo kicks in (for example, let's say it is at it's max):
BCLK = 133
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 24

RAM Speed = BCLK x Memory Multiplier = 133 x 10 = 1333 MHz
CPU Speed = BCLK x CPU Clock Ratio = 133 x 24 = 3.20 GHz


With 1600 RAM and XMP on
BCLK = 160
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 17

RAM Speed = BCLK x Memory Multiplier = 160 x 10 = 1600 MHz
CPU Speed = BCLK x CPU Clock Ratio = 160 x 17 = 2.72 GHz

With 1600 RAM and XMP on, when Turbo kicks in, assuming it's turned on (for example, let's say it is at it's max):
BCLK = 160
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 24**

RAM Speed = BCLK x Memory Multiplier = 160 x 10 = 1600 MHz
CPU Speed = BCLK x CPU Clock Ratio = 160 x 24 = 3.84 GHz

**I haven't tested an i5 750 with 1600 RAM and XMP and Turbo turned on to know if this is how it will actually handle the Turbo mode. (If you do run in this mode, please test it and let me know if my hypothesis is correct. It's possible the turbo doesn't ramp the cpu multiplier all the way up to 24. And of course some boards may not change the BCLK to 160 and CPU multiplier to 17.) However, based on my testing with an i7 860, to enable Turbo with XMP on in this scenario you will have to specifically enable Turbo AND set your i5 750's CPU Clock Ratio to 20. This means that your system will be OCed to a pre-Turbo level of:
With 1600 RAM and XMP on and CPU Clock Ratio to 20 when Turbo and EIST are not in effect:
BCLK = 160
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 20

RAM Speed = BCLK x Memory Multiplier = 160 x 10 = 1600 MHz
CPU Speed = BCLK x CPU Clock Ratio = 160 x 20 = 3.20 GHz

As I said before, you're overclocking now and you'll want to test your system for stability running at these settings. Keep an eye on Voltage and heat. Also, although I used XMP as an example you could accomplish the same thing by setting the memory multiplier, timings and voltage by hand.
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January 17, 2010 7:23:55 PM

so i guess i should buy 1333 speed ram, or what cpu can i run 1600 ram? or is oc'ing the ram a little a big deal?
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a b } Memory
January 17, 2010 7:34:06 PM

slick2010 said:
so i guess i should buy 1333 speed ram, or what cpu can i run 1600 ram? or is oc'ing the ram a little a big deal?

You can run 1600 RAM with an i7 860. When you have time to digest my last post (sorry it's so long) you'll see that with an i5 750 you can't OC your RAM over 1333 without OCing your CPU.

As I mentioned, there can still be some advantages to getting 1600 RAM. For example, if you're going to overclock it can give you more headroom. Also, every once in a while you can find 1600 RAM with equal or lower CAS ratings for the same or cheaper price. You just then will be running them at 1333 MHz. Another reason is that if you have 1600 RAM you might be able to run it at 1333 with faster timings, but it is hard to count on that until you get the RAM and test it. But if 1333 with low CL ratings is cheaper than 1600 RAM with comparable CL, and you don't plan on OCing, then it would seem 1333 MHz RAM is the better bet.
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January 17, 2010 7:50:18 PM

im running an e8500 now with 4 gb's 1066 ram, is it worth the upgrade or am i wasting $, im getting ready for bad company 2 and i here its going to run best with a quad core cpu
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a b } Memory
January 17, 2010 7:55:21 PM

slick2010 said:
Does lower voltage equal less performance? Im looking at some memory for a new build.

G.SKILL ECO Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL8D-4GBECO - Retail


or this

CORSAIR XMS3 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) ... - Retail

thanks


Lower voltage usually indicates better parts: Lower-quality parts generally need more voltage to remain stable. As for memory, you should look at this review:

http://www.tomshardware.com/reviews/ddr3-4gb-p55,2462.h...

Notice that the memory without sinks won, and for a couple reasons: It's better memory (duh) and it doesn't have heat spreaders.

I can confirm now that the Patriot DDR3-1600 in that article is the SAME RAM as the Crucial DDR3-1333. Why did the Crucial win? Probably becuase it runs cooler even when overclocked at 1.65V.

Why would it run cooler with no sinks? Probably because the thermal tape used to attach the sinks HINDERS heat transfer more than the sinks can help.

You'll get terrible advice from people who like shiney things in ALL user forums, though this forum isn't as overrun by that ideology as most others. Obviously, the RAM without sinks isn't as pretty, but it performs better.

That's not to say that all RAM with sinks is junk, it's just that the lower voltage used on Core i7 and i5 has made the sinks unneccessary and worse, that most or all the reasonably-priced RAM with sinks...have the sinks applied poorly.
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January 17, 2010 7:57:07 PM

im running an e8500 now with 4 gb's 1066 ram, is it worth the upgrade or am i wasting $, im getting ready for bad company 2 and i here its going to run best with a quad core cpu
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a b } Memory
January 17, 2010 8:22:01 PM

Crashman said:
Lower voltage usually indicates better parts: Lower-quality parts generally need more voltage to remain stable. As for memory, you should look at this review:

http://www.tomshardware.com/reviews/ddr3-4gb-p55,2462.h...

Notice that the memory without sinks won, and for a couple reasons: It's better memory (duh) and it doesn't have heat spreaders.

I can confirm now that the Patriot DDR3-1600 in that article is the SAME RAM as the Crucial DDR3-1333. Why did the Crucial win? Probably becuase it runs cooler even when overclocked at 1.65V.

Why would it run cooler with no sinks? Probably because the thermal tape used to attach the sinks HINDERS heat transfer more than the sinks can help.

You'll get terrible advice from people who like shiney things in ALL user forums, though this forum isn't as overrun by that ideology as most others. Obviously, the RAM without sinks isn't as pretty, but it performs better.

That's not to say that all RAM with sinks is junk, it's just that the lower voltage used on Core i7 and i5 has made the sinks unneccessary and worse, that most or all the reasonably-priced RAM with sinks...have the sinks applied poorly.


slick2010 said:
im running an e8500 now with 4 gb's 1066 ram, is it worth the upgrade or am i wasting $, im getting ready for bad company 2 and i here its going to run best with a quad core cpu


Generally speaking, there's very little to gain from moving from 1066 to 1333 on the E8500 because the CPU FSB is your bottleneck. I'd suggest overclocking the CPU FSB to get the CPU faster, the FSB faster, and the memory faster all at once. If the RAM is DDR3 running at 1.50 volts, you should be able to get it stable at 1280 (FSB-1600, aka 400 MHz FSB clock) simply by increasing the voltage to around 1.60-1.65 volts. That same FSB will take the CPU to 3800 MHz, which will probably require around 1.35 volts to the core.

Of course you can also increase FSB and not overclock the core by dropping the CPU multiplier, removing the need to increase CPU core voltage. Your 3.16 GHz CPU should run at 3.20 GHz (a mild overclock that doesn't require added voltage) by setting the FSB clock to 400 MHz and the CPU multiplier to 8x. You'll still get the faster FSB this way, your memory will still run DDR3-1280, and you'll still likely need around 1.65V DIMM voltage to make it stable.
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January 17, 2010 8:43:30 PM

is it worth going from what i have to the i5 with 1333 ram?
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January 17, 2010 9:15:47 PM

what if i went with this cpu?

Intel Core i7-860 Lynnfield 2.8GHz, could i then use ddr3 1600?
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a b } Memory
January 17, 2010 10:17:45 PM

slick2010 said:
what if i went with this cpu?

Intel Core i7-860 Lynnfield 2.8GHz, could i then use ddr3 1600?


You've already seen a link that shows that DDR3-1600 doesn't provide a noticeable performance benefit compared to DDR3-1333, but yes the i7-860 does support the higher speed. As for your old RAM, using it in the new system really depends on the voltage required to make it run the way you want, since the new CPU's onboard memory controller will require no more than 1.65V is applied to stay within its warranty

But you shouldn't use DDR3-1600 anyway. Look at my link above. You should use DDR3-1333, without sinks, and if you really want the extra speed you should overclock it to DDR3-1333.

Notice I said that Crucial's DDR3-1333 and Patriot's DDR3-1600 are the same parts. That's completely true. Patriot's DDR3-1600 is nothing more than DDR3-1333 that's been rated by the manufacturer at an overclocked setting.

In fact, MOST DDR3-1600 is rated at an overclocked setting and actually uses slower chips.
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January 17, 2010 10:45:01 PM

would the i7-860 cpu be a good upgrade from a e8500? whats the best memory to use with a i7? im just a little unclear about y u would run 1333 memory if the i7 can handle more
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a b } Memory
January 17, 2010 10:52:27 PM

Re-read the links that crashman and I have posted. There is very little - if any - performance difference beetwen 1333 and 1600.

What qualifies as a "good upgrade" is fairly subjective. What is your primary use for this going to be? How much money do you want to spend? What's wrong with your current system, or what do you want to improve about it? Maybe you should start a post in the homebuilt section following the guide stickied there: http://www.tomshardware.com/forum/261222-31-build-advic...
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a b } Memory
January 17, 2010 11:53:03 PM

slick2010 said:
would the i7-860 cpu be a good upgrade from a e8500? whats the best memory to use with a i7? im just a little unclear about y u would run 1333 memory if the i7 can handle more


In additions to what ekoostik just said, it appears that you're not paying attention to what I said about the DDR3-1333: DDR3-1600 IS DDR3-1333 It's not clear to me why you would pay another company to tell you that its 1333 is 1600, when you can simply use the same settings with memory that's labeled 1333. The reason I recommended this specific 1333 is that in Tom's Hardware's tests, it overclocked better and achieved better timings than most of the stuff labeled DDR3-1600.

But getting back to what ekoostik said, you don't get a noticeable performance gain from using your memory at 1600 MHz data rate.

So, you have two things: First, you don't need to run 1600 MHz data rate. Second, if you still wanted to run 1600 MHz data rate, you could do it better by using the high-quality DDR3-1333 I referred you to.

Read the links!
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a b } Memory
January 18, 2010 12:10:53 AM

Crashman said:
Probably because the thermal tape used to attach the sinks HINDERS heat transfer more than the sinks can help.

Thanks for the insight, I hadn't considered that before. I had wondered if they were completely unnecessary at the lower Vs for a lot of RAM getting turned out these days, but hadn't occured to me they might actually be getting in the way.
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a b } Memory
January 18, 2010 12:44:30 AM

ekoostik said:
Thanks for the insight, I hadn't considered that before. I had wondered if they were completely unnecessary at the lower Vs for a lot of RAM getting turned out these days, but hadn't occured to me they might actually be getting in the way.


Yes, the comparison I linked showed that modules with the same chips performed better without heat spreaders.

I think that higher voltage might necessitate voltage spreaders, because the higher quantity of heat could be dispersed more effectively by some of the larger spreaders out there. That is to say, the higher heat might bridge the threshold where the sinks are a bigger help than the tape is a hindrence. But we don't use high-voltage RAM with Core i5/i7, so the insulating effect of tape is the overwhelming factor.
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January 18, 2010 10:25:14 AM

so u guys would run 1333 memory with a i7-860 cpu?
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a b } Memory
January 18, 2010 11:18:11 AM

slick2010 said:
so u guys would run 1333 memory with a i7-860 cpu?


I would run exactly the DDR3-1333 memory I pointed to on an i7-860. And because it runs so much better than most DDR3-1600 when set to DDR3-1600, I would get that free 0.2% performance advantage by setting it to DDR3-1600. Why not do that when it's free?

I'm telling you it's better memory and it's usually cheaper than DDR3-1600. I've already proven that it's better than "typical" DDR3-1600 by pointing to an article where it outperformed "typical" DDR3-1600. Quit thinking that it's too good to be true and start doing a little research.
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