# RAM: Latency vs Speed???



## webJockey (Jan 5, 2010)

RAM: Latency vs Speed???

Hi guys, just confused in selecting right ram for my rig. With my budget I can only choose one thing. Either better latency or better speed. Can’t afford both. No plan of OCing ram at thus stage

So here are the choices:

CORSAIR XMS3 6GB (3 x 2GB) DDR3 1333. Cas Latency: 7. Timing: 7-7-7-20. Voltage: 1.5v Model:TR3X6G1333C7 G

CORSAIR XMS3 6GB (3 x 2GB) DDR3 1600. Cas Latency: 8. Timing: 8-8-8-24. Voltage: 1.65v Model:TR3X6G1600C8 G

I do HD video editing. NO GAMING AT ALL. Which one will perform better. Any feedback will be highly appreciated.

Thanks in advance 

System Configuration:
Processor: i7 920 (OCed 3.8Ghz)
Mobo: Asus P6T 
GPU: ASUS Radeon HD 4670 
PSU: Corsair 520w Modular HX520


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## Fourstaff (Jan 5, 2010)

How about better latency and then oc the speed? If you dont game, then both of them is pretty the same, my vote goes to better speed.


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## jjFarking (Jan 5, 2010)

Not sure you'd notice the difference actually..
The other thing is, those Corsair's happily run at lower latencies with increased voltages. As in your example, running the 1600 modules @ 1.8v should allow you to run them at 7-7-7-20 anyways


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## webJockey (Jan 5, 2010)

jjFarking said:


> Not sure you'd notice the difference actually..
> The other thing is, those Corsair's happily run at lower latencies with increased voltages. As in your example, running the 1600 modules @ 1.8v should allow you to run them at 7-7-7-20 anyways



I have read somewhere that voltage should not be more than 1.65. otherwise i may burn the things


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## douglatins (Jan 5, 2010)

webJockey said:


> RAM: Latency vs Speed???
> 
> Hi guys, just confused in selecting right ram for my rig. With my budget I can only choose one thing. Either better latency or better speed. Can’t afford both.
> 
> ...



OMG OMG OMG


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## jjFarking (Jan 5, 2010)

It does obviously depend on the specific models. That said, however, Corsair is one of those companies that test their RAM at higher voltages than the release models - ensures durability & quality control is second to none (well, kind of).


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## slyfox2151 (Jan 5, 2010)

Best not to go over 1.65 with an I7, 

You should grab the 1333mhz 7-7-7-20 @ 1.5v

Up the volts to 1.65 and see if they can run at 1600mhz 7-7-7-20


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## DrPepper (Jan 5, 2010)

Higher speed even with the higher latency is faster.


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## jjFarking (Jan 5, 2010)

slyfox2151 said:


> Best not to go over 1.65 with an I7,
> 
> You should grab the 1333mhz 7-7-7-20 @ 1.5v
> 
> Up the volts to 1.65 and see if they can run at 1600mhz 7-7-7-20



Agreed. The lower the voltage you can get the RAM stable at with lower latency, the better it is of course.
I merely mentioned the fact that Corsair is not afraid of higher voltages


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## jjFarking (Jan 5, 2010)

DrPepper said:


> Higher speed even with the higher latency is faster.



Don't you mean lower latency?


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## slyfox2151 (Jan 5, 2010)

DrPepper said:


> Higher speed even with the higher latency is faster.



Pritty sure id take that with a grain or 2 of salt...




lower ram timing's with lower speed is faster in WINRAR.


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## DrPepper (Jan 5, 2010)

jjFarking said:


> Don't you mean lower latency?





slyfox2151 said:


> Pritty sure id take that with a grain or 2 of salt...
> 
> 
> 
> ...



Check the benchmarks in my sig. 1600 at CL8 is faster than 1333 at CL7


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## slyfox2151 (Jan 5, 2010)

the problem is not if the ram can take the voltage but the CPU.

it is stated by intel that anything over 1.65 can damage the cpu .. IIRC


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## slyfox2151 (Jan 5, 2010)

DrPepper said:


> Check the benchmarks in my sig. 1600 at CL8 is faster than 1333 at CL7



where is the WINRAR benchmark? i couldnt find it.


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## jjFarking (Jan 5, 2010)

Interesting article.
What interests me there is the latency you got. Clearly the lower latency RAM should have scored lower, but didn't. That indicates an issue with either that particular RAM, or the way the mobo/CPU handles it.
There's no way on this green earth that 7-7-7-20 would have a greater latency than 9-9-9-24 timings.
Throughput changes with the increase of RAM speed, but access speed is critical in other areas.
Convince yourself with wPrime.
Keep the speed the same, but lower the latency and see just how much that's affected by the change..

EDIT:
I have two older results
Latency 9-9-9-24 (1333MHz):





Latency 7-7-7-20 (1333MHz):


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## DrPepper (Jan 5, 2010)

slyfox2151 said:


> where is the WINRAR benchmark? i couldnt find it.



Damn never noticed it was missing.



jjFarking said:


> Interesting article.
> What interests me there is the latency you got. Clearly the lower latency RAM should have scored lower, but didn't. That indicates an issue with either that particular RAM, or the way the mobo/CPU handles it.
> There's no way on this green earth that 7-7-7-20 would have a greater latency than 9-9-9-24 timings.
> Throughput changes with the increase of RAM speed, but access speed is critical in other areas.
> ...



Actually that's how it works the faster speed actually reduces latency, despite higher timings.


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## jjFarking (Jan 5, 2010)

Right.
So my old DDR1 RAM @ 400MHz had a latency of 42ms with 2-2-2-5 timings, whereas my 1333MHz DDR3 RAM has a latency of 52.7ms # 9-9-9-24 timings, but the DDR3 has reduced latency nonetheless?
How does that work?
Latency dictates access speed. MHz dictates throughput per clock cycle.
Increased speed by no means decreases latency..


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## DrPepper (Jan 5, 2010)

jjFarking said:


> Right.
> So my old DDR1 RAM @ 400MHz had a latency of 42ms with 2-2-2-5 timings, whereas my 1333MHz DDR3 RAM has a latency of 52.7ms # 9-9-9-24 timings, but the DDR3 has reduced latency nonetheless?
> How does that work?
> Latency dictates access speed. MHz dictates throughput per clock cycle.
> Increased speed by no means decreases latency..



Increased speed does = less latency. That's what all the test's show. If you stick your ram at 1600mhz 8-8-8-24 against your 1333mhz at CL7 the latency will be lower for the 1600mhz. I've ran those test alot of times and I always get the same results even on diffent computers.

Why have you got your 1333mhz ram at CL9 ? That's rediculously high for that speed. I run CL9 for 1866mhz. Explains your high latency.


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## jjFarking (Jan 5, 2010)

Everest's Latency Test - Basic results included in the program:




Notice a trend?
One thing to consider also is the command rate. Obviously, CR1 is better than CR2


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## jjFarking (Jan 5, 2010)

DrPepper said:


> Why have you got your 1333mhz ram at CL9 ? That's rediculously high for that speed. I run CL9 for 1866mhz. Explains your high latency.



That's the default latency of this RAM.. Sucks, I know, that's why I decreased it


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## DrPepper (Jan 5, 2010)

Okay here's my results 
	

	
	
		
		

		
		
	


	




If I go to 1833mhz and oc my cpu I can get the top spot on this chart.


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## jjFarking (Jan 5, 2010)

Hmm.. Why are you running CR2?
No wonder your latencies can be relaxed so much


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## DrPepper (Jan 5, 2010)

jjFarking said:


> Hmm.. Why are you running CR2?
> No wonder your latencies can be relaxed so much



Yeah I get the best results using CR2.


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## jjFarking (Jan 5, 2010)

Is there a chance you can OC your RAM only & see what the latency difference is?
Increased CPU speed will affect the latency somewhat as well, so to test the theory, only the RAM should run faster..


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## webJockey (Jan 5, 2010)

jjFarking said:


> Is there a chance you can OC your RAM only & see what the latency difference is?
> Increased CPU speed will affect the latency somewhat as well, so to test the theory, only the RAM should run faster..



I dont wanna touch ram at this stage.


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## DirectorC (Jan 5, 2010)

Conclusion: As you can see from the benches, the differences are minuscule.


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## majestic12 (Jan 5, 2010)

If you don't want to mess with the memory too much, I'd say you'd be completely in spec with the 1333 if you overclock your chip (i7 920 DO right?) to 3.33 Ghz -All you'd have to do is change the base clock from 133 to 166 and your RAM should automatically be moved to 1333 from the default i7 speed of 1066, permitted you keep the memory timings the same.  This is a basic overclock though (no changes to CPU voltages or anything like that and memory is running at rated speed). Of course faster memory can't hurt so the 1600 will give you more headway if you decide to push it more.  Even without an overclock, most motherboards' BIOS's are really easy to set the timings in so I'd go for the 1600.


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## slyfox2151 (Jan 5, 2010)

DrPepper said:


> Okay here's my results http://img.techpowerup.org/100105/Capture002257.jpg
> 
> If I go to 1833mhz and oc my cpu I can get the top spot on this chart.





wierd, going to do some benchmarking on my system again to see if i can get lower latency with higher bandwidth / timings,


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## EastCoasthandle (Jan 5, 2010)

Why not get the 6Gig DDR3 ULTRA TRIPLE CHANNEL DDR 31600MHz C7.  This is tested to work on your motherboard.


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## webJockey (Jan 5, 2010)

i ben tempted to c7 but heres something new. newegg says its the ultimate memory for i7. check here

however corsair does not list it in recommended memories for i7. check here.


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## MilkyWay (Jan 5, 2010)

might be faster for intel cpus to have faster ram than tighter latencies but thats not the case for AM3

for that it likes tighter but ideally because AM3 can go over 1.65v for safe you can get higher clocking and tighter at the same time

overall ram is expensive so 1333mhz sticks might be all you can afford like me!


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