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DDR3 1600 CAS 9 vs. DDR3 1333 CAS 7

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June 18, 2011 9:54:28 PM

After much research, I'm set on building a system around i7-2600K on an ASUS P8P67 Deluxe board. I might try overclocking, I might not.

For RAM, I'm looking to spend less than $200. 16GB (4 x 4GB) seems within reason. Given the requirements of 240-pin, DDR3, then my options are:

1. DDR3 1600 with a CAS Latency of 9 or
2. DDR3 1333 with a CAS latency of 7

If I understand correctly, DDR3 1600 is faster than DDR3 1333 (but only if overclocking, maybe? yes? no?). On the other hand, CAS 9 is slower than CAS 7, right?

These are the options I'm considering.

What are your recommendations and reasoning?

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a c 347 } Memory
a b K Overclocking
June 18, 2011 10:08:59 PM

I've seen more problems with Ripjaws X in 16GB configurations and have often recommend the Corsair CMZ16GX3M4A1600C9B {note: if your HSF is low and covering the DIMM slot closets to the CPU you might have a height issue.}

Alternative, are the Ripjaws X F3-12800CL9Q-16GBXL {if necessary they can run 1333 CAS 8-8-8-24-2T @ 1.5~1.55v}. The problem is rare and typically with Gigabyte MOBOs.

1600 CAS 8/9 is the SB sweet-spot, nice article -> http://www.bit-tech.net/hardware/memory/2011/01/11/the-...
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a b } Memory
a b K Overclocking
June 18, 2011 11:55:56 PM

ddr3 1333 7-7-7-21 is actually more efficient than the ddr3 1600 9-9-9-28. it will give more bandwidth to the cpu so the whole system is more efficient in how it handles your data.

the advantage of slower but 2 lower on cas latency will give the equivalent usage of ram that is about 500mhz faster. so 1333 cl7 will be as efficient as 1800 cl9 ram.
the advantage of 1600mhz cl9 ram is it can often tighten the latency to 8-8-8-24
and give the equivalent performance of 2000mhz cl9 ram

rite now there is some cl7 1333 ram that will quite happily run at 1600mhz oc'd with its cl7 settings and that stuff will out perform 2100+ ram with cl9 settings... so its always worth checking the oc ability of slower ram as it may just surprise you.
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a c 347 } Memory
a b K Overclocking
June 19, 2011 12:32:38 AM

I wish it was according to 'Charts', it's not. The IMC speed, 'BCLK' Base Frequency, quality RAM IC, etc all affect performance. In other words, a quality IC vs a value IC with a lower notch CAS might perform equally with peak transfer rates.

The SB isn't like the i7 9XX w/ adjustable BCLK instead the Base Frequency it's fixed, so performance isn't hugely affected or managed. The SB looks at frequencies >1600 MHz and CAS variations with a blank stare. It depends upon the tests. The first week out I was advocating 1866 MHz low CAS RAM for the SB until tests illustrated a 'wall' with the SB.

Synthetic aside, I would encourage you look at the Bench Tests as I linked above :) 


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a b } Memory
June 19, 2011 12:45:40 AM

DDR3 1333 with a CAS latency of 7

Because you are guaranteed to be able to achieve that configuration. 1600 is technically out of spec and often people have problems getting their system stable with that RAM clock *especially* with 4 sticks of RAM. The good news is, even if you get 1600 RAM, you can probably run it at 1333 with CAS7 timings if you want. :) 

16 GB? Really? :) 
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a c 347 } Memory
a b K Overclocking
June 19, 2011 1:18:54 AM

In a few post back some OP wanted 32GB until I showed them the price of 4X8GB :) 
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June 22, 2011 8:48:35 AM

jaquith said:
I've seen more problems with Ripjaws X in 16GB configurations and have often recommend the Corsair CMZ16GX3M4A1600C9B {note: if your HSF is low and covering the DIMM slot closets to the CPU you might have a height issue.}

Alternative, are the Ripjaws X F3-12800CL9Q-16GBXL {if necessary they can run 1333 CAS 8-8-8-24-2T @ 1.5~1.55v}. The problem is rare and typically with Gigabyte MOBOs.

1600 CAS 8/9 is the SB sweet-spot, nice article -> http://www.bit-tech.net/hardware/memory/2011/01/11/the-...



Let me clarify something that was not clear from your post:

it seems like, according to the article, GAMERS (specifically) will not see much benefit beyond 1600 mhz because the games themselves do not perform any differently above that speed. ON THE OTHER HAND, simple "multitaskers" WILL see a performance benefit from going above 1600 mhz.


Also, they used 16gb of Gskill ram (4x4gb) with a Gigabyte P67 UD7 board, and they only said they had to change the timings to get stable game performance at 2133 mhz. Is that the stability issue? I couldnt find any other references to it.



I ask (the first part) because you mentioned a "wall" in performance around 1600 mhz, but according to the article's conclusions (and their graphical representations of the results) multi-tasking applications will see a performance increase beyond 1600.... BUT the games will not.



"Meanwhile, the multi-tasking test showed a noticeable benefit in faster, lower latency memory, though. This is worth noting, since these are quad-core/eight-thread thread CPUs designed to do a multitude of things at once. The difference between the 1,333MHz kit at a sluggish CL9, and the 2,133MHz kit at CL8 was over 200 points."
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a c 347 } Memory
a b K Overclocking
June 22, 2011 6:05:13 PM

2133MHz on any Sandy Bridge is a hit or miss, in by miss I mean BSODs. Yes, you can raise the CAS timings to improve stability e.g. 9-11-9 -> 11-11-11 which is a real JEDEC standard; defeats the Frequency. I find RAM Mfg's try to get the magical CAS 9, but the CAS/frequency of problems warrants a careful look on motivation. IMO - Don't run 2133 MHz on SB, maybe 1866 MHz with a kit that offers a low tight CAS.

I generally recommend 4GB density/stick 1600 MHz CAS 8-8-8, and in the beginning I was an 1866 'pusher' but I was getting some blow-back.

Another nice Article -> http://www.tomshardware.com/reviews/ram-memory-upgrade,...

The 'Wall' 99% of these posts are for gaming, therefore there are a few things to consider:
1. Stability
2. Performance

Most people aren't multi-tasking freaks they're Gamers and sometimes Render'ers who don't want a BSOD 2 hours into their games or CAD/Rendering work, and the 1600 MHz CAS 8/9 is a WALL to the Games and GB's of RAM to the Render's. There is more than one article to substantiate the benchmarks.

I run 2000MHz on my OC 980X {BCLK + CPU Multiplier} where I can adjust my BCLK to achieve greater stability, those days are gone with Intel, I'd guess for good.
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June 25, 2011 11:42:13 PM

cscooper2000 said:
After much research...
For RAM, I'm looking to spend less than $200.
What are your recommendations and reasoning?


You need to research more. There are some good deals on DRAM out there right now.

I just picked up 16gb of 9-9-9-24 for $55.
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a c 347 } Memory
a b K Overclocking
June 26, 2011 5:10:48 PM

Here's the issue in a nutshell, if you have an UNLIMITED budget then get any damn thing you can dream of and if it includes 2133 or 2200 MHz RAM go for it.

However, for just about anything else having the same GB's of RAM example 2x4GB or 4x4GB, save the MONEY and increase your GPU.

Example:
$306 F3-17600CL9D-8GBXLD 2x4GB 2200 MHz
$160 MSI N460GTX Hawk GeForce GTX 460
====
$466

$65 F3-10666CL9D-8GBNT 2x4GB 1333 MHz
$317 EVGA 012-P3-1570-AR GeForce GTX 570
====
$382 {-$84}

Savings $84 and trust me the $84 cheaper setup will kick the crap out of the more expensive setup.

Lesson, the costs of 2133 MHz is completely unjustified and you're crazy to argue it is justified.

---
The lowest priced NEW 4x4GB is F3-8500CL7Q-16GBRL at $150 at Newegg, so $55 DDR3 4x4GB I assume is eBay.


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June 17, 2012 2:52:22 PM

i think that if you will buy 16GB of 1333 memories it will do the job... it is doing a great job in my computer when one of my friends bought a very common computer and it isnt a big change... tested in BF3...
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