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RAM speed and timing questions

Last response: in Memory
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May 30, 2012 3:56:07 PM

I have an Asus P8Z77-V Pro motherboard and the memory supported is 1600MHz and anything higher will have to be overclocked. This is the pair i was looking at

G skill ripjaws x
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Cas Latency: 8
Voltage: 1.5V
Timing: 8-8-8-24

now i know for the most part over 1600 you wont notice a difference but this set of RAM is the exact same price

G skill sniper series
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Cas Latency: 9
Voltage: 1.5V
Timing: 9-10-9-28

so my question is even though the difference is barely noticable should i get the 1866MHz for the same price and when it defaults to 1600 just change it to 1866? and does this mean i would have to up the voltage?

i am also a little confused when it comes to CAS latency and timings..from everything ive read the lower the better...

so i dont really know which would be better in the situation for the same price..

the 1600 MHz CL 8 8-8-8-24
or the
1866 MHz CL 9 9-10-9-28

if someone could please help out id really appreciate it..i know theres a couple different questions in my post so if you know about them feel free to explain everything..thanks
a b } Memory
May 30, 2012 5:19:58 PM

Hard to tell you which would be faster. My DDR3-1333 kit runs at CAS 7, but I can overclock it to DDR3-1600 if I loosen it to CAS 9. Benchmarks show a slight gain in speed at 1600/CAS 9.

For the most part though, there is little benefit to faster memory. You start getting pretty big diminishing returns after DDR3-1600.

If I had to guess, I'd say that the DDR3-1600 at CAS 8 will be within a few percent of the DDR3-1866 at CAS 9, might even be a tad faster.
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May 30, 2012 5:32:24 PM

thanks..anyone else know which would be best?
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May 30, 2012 9:02:46 PM

to help you understand, ddr3 1333mhz at cas 7 is identical in performance to a fictional ddr3 2666mhz at cas 14.

since there's little difference between the two in terms of performance, if i were u, id go with the 1866 as it is tested at a higher frequency and will (potentially) give me better overclocks. if i hit a snag in overclocking due to the ram, i can always underclock the ram to 1600 in order to reach a higher cpu overclock.
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a c 85 } Memory
May 30, 2012 9:40:59 PM

check that the ram has been tested by the mb vendor or the ram vendor for your board. you dont want to return the ram if it wont work in your mb.
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a b } Memory
May 30, 2012 11:18:12 PM

Quote:
ddr3 1333mhz at cas 7 is identical in performance to a fictional ddr3 2666mhz at cas 14.

Okay, lets introduce some math...if performance is a ratio of MHz/CL as suggested above by jbseven.

Then 1600MHz/8CL=200PP (performance points)
and 1866MHz/9CL=207.33333PP


Following this to its logical conclusion, shopping for RAM by this method, I browsed Newegg for 8GB (2x4GB) dual channel kits and ran the numbers:
For best PP/Dollar:
Team Xtreem LV Series at 1600MHz/7CL=228.56PP @ $52= 4.4PP/Dollar

For most PP overall:
Team Xtreem LV Series at 2400MHz/9CL=266.666PP @ $130=2.05PP/Dollar

So in your case I would actually recommend the Team Xtreem 1600MHz.
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May 30, 2012 11:32:44 PM

I posed a very similar thread last year..let me find it.

Memory Speed vs. Timings - Experts wanted.

In the end, I actually got Corsair Vengance 8GB (2x4GB) DDR3-1600. Just bumped it to 16GB, only because it's cheap. (8GB for $50!)
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May 31, 2012 3:25:48 AM

I wouldnt go with the team extreme unless it was in the supported memory list for ur board simply because ive never used them and the one reviewer on newegg said 'go with something more reliable'.
i doubt u'd have compatibility issues with corsair, g.skill, etc.
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a b } Memory
May 31, 2012 4:32:51 AM

Not need to go over 1600 except u do lots of converting.....

I will buy cheap 1600 CL9, and oc it to CL8, most ram can do that small oc.. (Er.. not so cheap one...)
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a b } Memory
May 31, 2012 3:06:46 PM

My assessment was purely based on the MHz/CL/USD ratio and did not take any brand or review into consideration. By large, most RAM that fits withing the specifications required by the motherboard (DDR3 1066/1333/1600/1866(OC)/etc) will work, not to say that there may be instances where it doesn't. If it were my money I was spending I would chose a brand that I am familiar with.
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a b } Memory
May 31, 2012 4:04:45 PM

aholeinthewor1d said:
thanks..anyone else know which would be best?

Between 1GHz and 2GHz DDR3, most real-world benchmarks only show ~2% performance improvement so RAM performance is not really worth worrying about. Which of the two would be best also varies depending on what sort of access patterns are predominant in the games and applications you use most. Code with a largely linear structure like video processing would benefit most from higher bandwidth while highly conditional code like compilers would benefit more from low latency. Games are mixed bags of linear geometry/physics processing and conditional AI/control/script code which makes the answer a case-by-case thing.

Either way, the difference will be slim. I personally would pick lower latency at 1600MHz.
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