Whcih speed ddr3 for i5 750

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jimmy999

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Jan 7, 2010
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Hi sorry for sounding nooby, but im about to order my first build, got everything sorted but the ram!

Just wondering which speed will be best?

Im going to be running an i5 750 and an Gigabyte GA-P55-UD3, want to overclock to around 4ghz mark

which speed ram would be best for this?

also on a side note the memory support list says it supports kingston but the code is different for every speed, would the ram still work if not listed on gigabyte website?
 
Do you plan on overclocking your CPU? Do you like to mess with the various RAM timing settings? If the answer to both of those questions is No, then I would recommend 1333 speed RAM with the lowest CAS rating you can afford.

By default the socket 1156 CPUs run at a BCLK = 133. The system memory multiplier is 10x (10x133=1333MHz). The i7 860's (as an example) CPU clock ratio (cpu multiplier) is 21x (21x133=~2.8GHz).

With an i7 860 you are allowed to up the memory multipler to 12x fairly easily, depending on the motherboard. And Gigabyte makes this easy. However, an i5 750 cannot go higher than the 10x memory multipler. This means at stock bclk the fastest you can set the RAM to is 12x133 = 1600MHz for an i7 860. While for the i5 750 the fastest you can set the RAM to is 10x133 = 1333MHz. To get any faster you have to OC your CPU.

The reason I asked if you like to tweak the timings of your RAM is that in theory if you buy RAM rated at 1600 but only run it at 1333 you should be able to tighten the timings. But it certainly would be easier to just get 1333 RAM spec'd with a lower CAS latency.


If you want to do some reading on speed differences, I suggest reading these 2 articles:
http://www.tomshardware.com/reviews/memory-scaling-i7,2325.html
http://www.anandtech.com/memory/showdoc.aspx?i=3589

The differences between each step up in RAM is often marginally noticeable, and outside of a benchmark it is difficult to say whether or not you would even notice the difference. And yet the cost difference adds up fast. The best advice I got from these forums was buy the best RAM that fits your budget, if you find yourself stretching things just to get 'better' RAM that's probably money better spent on other components.

Both of those articles were written about the i7 9xx / 1366 socket chips. I haven't seen a lot of articles specifically focused on RAM speeds on the P55 platform. However, Tom's did a review of value RAM you may also find interesting: http://www.tomshardware.com/reviews/ddr3-4gb-p55,2462.html

And one final article from Tom's: http://www.tomshardware.com/reviews/core-i7-870-1156,2482.html
I didn't care for the way results are presented, to me it's not as clear cut. 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 may be worth a read.
 
if i may, have kind of a similar question.
planning to buy i5 750 brand new system.
i can get each of those in almost the same price. 2x2 gb.

G.Skill Ripjaws Edition Dual Channel 7-7-7-24 1.65 v 1600 mhz

G.Skill Ripjaws Edition Dual Channel 7-7-7-21 1.5 v 1333 mhz

i`ve been told that some applications will benefit from 1600 mhz, compare to 1333.
also in the article you linked they say:
"Go for a faster product if you find DDR3-1600 memory that provides the same timings as your preferred DDR3-1333 RAM kit at only a little price premium."

i`m not planning oc, yet my question is: i know that the i5 have a turbo mode.
dosen`t it raise the mhz during operation in a way that will effect the speed potential concerning this memory issue ?
the second question concerning to the volts .
most of 1600mhz ram comes with 1.65 v and the 1333 1.5 v.
i`m afraid that if i will not get any benefit from the 1600 mhz i`ll just pay the price of having higher volt, meaning more heat.

 
IF you get the 1600 mhz. modules and wind up using them at only 1333 you will probably find that they can also be run at the 1.5V (they are probably the same modules just rated differently with the voltage increase)
 
someone already told me that they are the same modules just they made to one of them some oc.
doe`s it mean that the oc one found as a better quality sticks , since they choose them to be oc?
how much is it a disadvantage to work with 1.65 v.
one of the problems is that most of the articles/benchmarks linked here refer to the i7 so i don`t know if i`ll be benefit from the 1600.
what is your recommendation if the price difference is very marginal and i`m willing to get the best.
 
Re-read my original post, especially the top half, the first four paragraphs. What I am saying there is the same things as what you found in the MSI forum.

With an i5 750 you cannot run RAM any faster than 1333 with effectively OCing your computer. You can turn on XMP, 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.

To answer your question about turbo, let me explain in a different way 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 essentially 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.

To your question about Turbo:
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 Turbo kicks in, it is the CPU Clock Ratio that changes. For example, with one core active Turbo might raise the CPU Clock Ratio as high 24. This gives the CPU a max speed of 133 BCLK x 24 CPU Clock Ratio = 3.20 GHz.

Because it is the CPU Clock Ratio that changes and NOT the BCLK, the RAM speed does not change.

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 20 = 3.20 GHz
 
wow, it shows me how much i don`t understand.
now it is a bit clearer.
so to sum it, the raise of the cpu clock in turbo mode will not effect the ram speed potential.
and if i`m not planning to "play" with my system (no oc and no the other things you mentioned, which i don`t even know what the most of them are, and certainly not how to do them) mainly to run it at default, i will not see any advantage with a 1600 mhz ram?

and this recommendation refer only to the i 7? ("Go for a faster product if you find DDR3-1600 memory that provides the same timings as your preferred DDR3-1333 RAM kit at only a little price premium." ).

and at last, if i can get each of them( 1333 and 1600) for a same price, same timings, probably same modules,
isn`t it worth to take the 1600 one , work with them on 1333 1.5 v, assuming that if they choose to oc those specific sticks they might found them better quality one`s/capable for better performance?
or there is another disadvantage by doing it, i don`t know about?






 

Correct

and this recommendation refer only to the i 7? ("Go for a faster product if you find DDR3-1600 memory that provides the same timings as your preferred DDR3-1333 RAM kit at only a little price premium." ).
Click to expand...
I believe that is right - that they were talking about the 1156 i7 8xx they tested with. But I linked four articles and I'm not exactly positive where that quote came from. If you provide a link to the article and page with that quote I'll give it another read.

and at last, if i can get each of them( 1333 and 1600) for a same price, same timings, probably same modules,
isn`t it worth to take the 1600 one , work with them on 1333 1.5 v, assuming that if they choose to oc those specific sticks they might found them better quality one`s/capable for better performance?
or there is another disadvantage by doing it, i don`t know about?
Click to expand...
I would agree with your statement - IF you can get the 1333 and 1600 for the same price, and if you can run the 1600 RAM at 1333 MHz with 1.5V, then the 1600 is the way to go. I can't speak to the V it will take to run those but the other posters seemed fairly confident about that.
 
I'm currently building an I5 750 as well, and have decided on the RAM (Gskill ECO series), but haven't purchased yet. Good thread fellas, as it's helpful to a lot of us who are building for the first time.

In a nutshell, would I be wrong to conclude that the 1333 speed RAM is perfect for anyone who is NOT looking to OC their system on their own, hence the advice to look for 1333 with the best timings. Whereas the 1600 speed RAM would be the right choice for someone who IS looking to OC their set up manually.

Is this accurate?

If so, or better yet, if someone is undecided about OC'ing down the road, would it be wise to invest in 1600 speed RAM, as a means to protect yourself, or "future proof" your ability to OC down the road? For $15 more I can step up the RAM to 1600 CS7 ECO RAM. Would this be a good investment since I'd like to eventually OC my i5 750?

Thanks in advance.
 

I found the quote you mentioned within that article: "Go for a faster product if you find DDR3-1600 memory that provides the same timings as your preferred DDR3-1333 RAM kit at only a little price premium." However, they follow that up with "Don’t do it if you could get a faster processor for less or the same extra money." In other words, don't spend extra money on faster RAM if that same money could get you a faster CPU. And I would add, or a faster GPU.

You had asked: "and this recommendation refer only to the i 7? ("Go for a faster product if you find DDR3-1600 memory that provides the same timings as your preferred DDR3-1333 RAM kit at only a little price premium." )."

I would say, yes the recommendation is only for the i7 8xx, because that is what they ran their tests on and it is not possible to run the i5 750 with 1600 MHz RAM without OCing the CPU. I would also point out that, even for the i7 8xx, they also say "go with brand-name memory at mainstream speeds, which still are in the DDR3-1333 space" and "Make sure you pick a branded product of at least DDR3-1333 speed and timings of CL8 or faster."

I don't know of a place off-hand to help w/ your V question.
 

Yes, I would say this is accurate for someone working with an i5 750. If you're working with an i7 8xx you can get 1600 (although there's little benefit over 1333 per the articles referenced above), or you can go faster if you're planning to OC.

If so, or better yet, if someone is undecided about OC'ing down the road, would it be wise to invest in 1600 speed RAM, as a means to protect yourself, or "future proof" your ability to OC down the road? For $15 more I can step up the RAM to 1600 CS7 ECO RAM. Would this be a good investment since I'd like to eventually OC my i5 750?

Thanks in advance.
Click to expand...
It's your (or the person's) $15, so I'll leave it to them to conclude how wise it is and whether it is worth it. I'm not a big fan of the phrase "future proof" as I think it's overused, often incorrectly or with no real meaning. However, your conclusion is valid. I would rephrase it a little and say that if you want to leave open the possibility to OC at some future point and do not want to have to purchase new RAM, then investing in faster rated RAM now may be a good investment.

(I should also point out it is possible to OC your system with "slower" RAM such as 1333. Since the 1156 CPUs share bclk, any time you OC the CPU you have to adjust the memory multiplier to keep the memory speed under its rated speed. It doesn't matter if you're using 2000, 1600 or 1333. But obviously the higher the rated speed, the more room you have to work with.)
 


Thanks for the reply eko, I think you made my choice a lot easier. I'm going to go with the 1600 ECO ram. Looks like it's this set for me.

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231321&cm_re=eco_1600-_-20-231-321-_-Product
 


since in my case it is less then 10$ difference i think i`ll take the chance and for the reasons i already mentioned i`ll go for the 1600 mhz.
thanks for all your help.
 
1600 MHz rated RAM with CL7 and only 1.35V. Looks like good RAM. I haven't looked at what's available in a number of months since I built my rig, which was before this eco ram came out. I'm a little surprised to see they got the V down that low!
 


i decided to do the same as you.

did you choose them for some reason, recommendation ?
i see they are working with very low volts, looks a bit strange for 1600 mhz.
i am thinking on those.
G.Skill Ripjaws Edition Dual Channel 7-7-7-24 1.65 v 1600 mhz



 

You're welcome. Enjoy the build.
 



Everyone I talked to, and most threads I read, tended to talk up these ECO sticks from Gskill. These and the Rip Jaws. With the voltage so low on these, they just seemed to make more sense than the Rip Jaws. Apparently Intel says not to exceed 1.65 volts for the i5 750. I figure the lower voltage makes sense power wise, and would be less stressfull on my system, especially if I crossfire down the road, and bump up to 8 GB's some day.
 
I got geil evo 1 2133 mhz ram which was overkill but the combo price made it semi affordable. I knew it was overkill but i didnt want it to limit my OC. now i am running it at 1700mhz and have experienced no problems at 1.65v. Has anyone experimented with overkill ram?
 
I second what Real World said, ECO RAM is awesome. I had Rip Jaws in my cart until researching the 1.35 Volt G.Skill.

I opted for 1333MHz 7-7-7-21 for my Core i7 860/ ASUS P7P55DE-Pro, first because of the low voltage, and second because it had chrome heat spreaders.

I have permenantly settled on 1775 MHz, 7-8-7-24 at ONLY 1.4 V

I did, however, run a while at 2000MHz, 9-9-9-27. I didn't have any crashes, but I refused to increase the voltage to make Prime95 run stable. I did extensive benchmarks on it and estimate it would be stable in Prime95 at 1.65V or so. Since that is what all the other RAM runs at, it is quite ahead of the game at the point. I prefer to keep my voltage way down and do some Green Computing.

I documented the whole overclocking process for the memory and the Core i7 with CPU-z and Core Temp screenshots. You can view each benchmark step http://solidlystated.com/hardware/core-i7-860-overclocking. Even before I settled on an overclocked speed, there really wasn't anything out there pushing the system limits. I am 100% happy with my ECO RAM.


Here's a link for this RAM

 
I too have an i5 750 on a ASUS P7P55D and in researching Ram, I too decided on 1600MHz ram for overclocking headroom. Here is my Ram:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820104142

Here is the data sheet:

http://www.valueram.com/datasheets/KHX1600C8D3T1K2_4GX.pdf

I have set my BCLK to 160, with turbo and all power savings on. Effectively giving me a overclock of 3.2 GHz, with turbo 3 or 4 cores 3.36GHz, and 1 or 2 cores up to 3.84GHz. At idle, the CPU still underclocks like stock, and there is very little rise in heat even running Prime95 or OCCT.

With the ram multiplier at 10x, my ram is running at it's native 1600MHz. I currently have my timings at 8-8-8-24. Would there be a measurable increase in performance at tighter timings, and how does one go about deciding what timings? In researching my ram, there is mention of 8-8-8-20 performance timing at 1600MHz, but what determines if one can go to 7-7-7-?, etc.

A Guy
 


You'll have to try it to find out whether or not that RAM can do it. The higher the frequency or the tighter the timings, the more unstable the RAM gets. You can increase stability by increasing voltage. This increases heat and can decrease lifespan.

To go from 8-8-8 to 7-7-7, you wouldn't have to increase it by much. You are at 1.65V stock, so 1.70 should be more than sufficient @ 1600MHz
 
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