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I7 ram speed vs latency

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October 27, 2010 5:13:09 PM

I wasn't sure if this would be better in the cpu or ram category so I took the lazy mans route and put it in the first category i came to.

From what i've read it seems that when choosing ram amd's seem to favour better latency whereas intels favour ram speed. As I understand it this is due to amd's having the ram memory controller integrated into the cpu and intels use the fsb memory controlled.

Well the i7's have now integrated the memory controller into the cpu. Does this now mean that if you are using an i7 latency is a more important feature than speed?

Of course increasing the latency is more important only once the ram reaches half the speed of the uncore. As I understand it that is.

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October 27, 2010 7:34:09 PM

I am interested in this topic as well. I found using sandra, that I have better efficiency with my ddr3 1600 @ cas 6 as opposed to cas 9 however at lower speeds, seems to be more responsive at higher cas ( could be a fluke) fi there are specific benches you would liek me to do on my i7, let me know I would love to help out here
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a b } Memory
October 27, 2010 7:57:36 PM

When it comes to RAM, the advantage of high clock speed and/or lower latency timings is more evident with synthetic benchmarks such as sandra, pc mark etc.. In real world, considering RAM modules from similar platforms, there is no apparent difference between CAS 7 and CAS 9 modules.. Higher clock speeds provide more room to achieve higher overclocks on the CPU but other than that, there is no real world performance gain going from DDR3 1333 MHz modules to DDR3 1600 MHz modules.. And all this is independent of the platform.. In other words, these characteristics remain the same be it on an Intel platform or an AMD platform..
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October 27, 2010 9:12:36 PM

maybe I will run some game benchmarks and maybe some compression benches as well to really look at the difference and get a better understanding
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a b } Memory
October 28, 2010 1:22:17 PM

Most applications are not limited by the bandwidth of the memory so increasing the clock speed often will not help it too much, but improving the timings can have a bigger impact due to faster response time on the memory, granted you are talking a few ns per word but it can add up significantly overtime. The timings are affected by the clock speed however so DDR3 1333MHz with CL7 and DDR3 1600 with CL9 will have about the same latency time, even though the number of cycles on the 1600MHz one is higher the faster clock speed brings it to about the same time so its a compromise. Most of the time the difference wont show up outside of benchmarks because even the theoretical differences are not huge.

Just try to get one thats a good mix of speed and timings, dont spend as much on a DDR3 1333MHz kit for CL6 when you could get a DDR3 1600MHz kit with CL7 that would be just as fast.
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October 28, 2010 5:59:53 PM

@hunter, maybe you could help me understand this... I recently built 2 machines 1 i5 750 with ddr3 1600 cas 7 and an i7 930 with ddr3 1600 cas 6 both overclocked to 3.8 the i7 just felt much more responsive is this just due to the triple channel memory or is there something I am missing? in theory you should not feel a difference between the 2. ( I used the same brand and model hard drive in each as well ( samsung F3 500GB) I look forward to your explanation.
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October 28, 2010 9:10:05 PM

Hard Line said:
@hunter, maybe you could help me understand this... I recently built 2 machines 1 i5 750 with ddr3 1600 cas 7 and an i7 930 with ddr3 1600 cas 6 both overclocked to 3.8 the i7 just felt much more responsive is this just due to the triple channel memory or is there something I am missing? in theory you should not feel a difference between the 2. ( I used the same brand and model hard drive in each as well ( samsung F3 500GB) I look forward to your explanation.


Could be anything - the increased memory bandwidth may have given a boost to the operation, the faster response of the CAS6 may also have helped, the i7's Hyperthreading may have made a difference for a change, a psychosomatic response/placebo effect because the i7 is supposed to be more powerful, better/worse motherboard, hard drive access times and I/O operations, the list goes on.


That being said, I have seen small but noticable improvements when using tighter timings on i7 900 systems - I have two i7 920 video edit suites at work, both with the same motherboard and 1600MHz RAM. One RAM set is at CAS7, the other at CAS9.

CAS7 system renders the same HD projects about 15-20 seconds faster consistently. Again, it could be anything, and even though it's a negligible difference, it's still a difference.
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October 28, 2010 10:58:04 PM

the i7 machien wasn't mine it was built for a friend and at the time I had an e7200 at 3.8 and it felt faster.. I think I just may blame mainboard on the i5 somehow slowed the i5 down. lol when my mainboard decided to cry mercy and die on me, I replaced with the i7
a c 81 à CPUs
a b } Memory
October 29, 2010 3:16:41 AM

Hard Line said:
@hunter, maybe you could help me understand this... I recently built 2 machines 1 i5 750 with ddr3 1600 cas 7 and an i7 930 with ddr3 1600 cas 6 both overclocked to 3.8 the i7 just felt much more responsive is this just due to the triple channel memory or is there something I am missing? in theory you should not feel a difference between the 2. ( I used the same brand and model hard drive in each as well ( samsung F3 500GB) I look forward to your explanation.


Did you supply both the platforms with same amount of RAM.? And where did you feel it to be extra responsive.? If you are just talking about the desktop experience then i guess its more of a psychological thing then a real happening event..
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October 29, 2010 12:16:56 PM

the i5 had 8GB and the i7 has 6GB ( which i am hoping to throw in another 6GB) the i5 had gskill eco cas 7 @ 1.35v and the i7 I have redline enhanced cas 6. when I had built them, I had expected them to be the same on the desktop and only see a difference in benchmarks. so i am not so sure it is the placebo effect.esp considering it feel about as responsive ( prob a little more) than my e7200
October 30, 2010 5:15:44 AM

I got an Asus Sabertooth with the i7-950. I got G.Skills and by manually setting the memory in the bios to 9-9-9--24, my system runs at 3.2Ghz, about a 5% performance increase. I use stock cooler and have no problems. In my warm computer room, iddle temp is about 50c and 60-70 when working. It will jump to 80, briefly peaking to 100 degrees centigrade when ripping video!
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October 30, 2010 12:55:12 PM

rafacq said:
I got an Asus Sabertooth with the i7-950. I got G.Skills and by manually setting the memory in the bios to 9-9-9--24, my system runs at 3.2Ghz, about a 5% performance increase. I use stock cooler and have no problems. In my warm computer room, iddle temp is about 50c and 60-70 when working. It will jump to 80, briefly peaking to 100 degrees centigrade when ripping video!



Dude, that's seriously too hot - 100 degrees is the CPU's safe limit to either throttle back or even shut down.

The Intel stock cooler is not designed to run the i7 950 at 3.2GHz so you're risking things a bit. If you're ripping video regularly I strongly recommend you get a better cooler - Coolermaster Hyper 212+ is a good one and cheap and will handle your overclock without a problem.


Apologies for the digression
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October 30, 2010 1:25:36 PM

I agree with LePhuronn... you definitely need an after-market cooler. the stock barely handles the default clocks +1 to the hyper 212+ ( just don't expect extreme overclocks with it )
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