A couple of quick questions on timings (when buying RAM)

[PiMan314]

So I am purchasing one of these two RAM kits:

8GB (2x4GB) Corsair DDR3 Vengeance Jet Black Low Profile, (1600), Non-ECC, CAS 7-8-8-24, XMP, 1.5V

8GB (2x4GB) Corsair DDR3 Vengeance Jet Black Low Profile, PC3-12800 (1600), Non-ECC, CAS 9-9-9-24, XMP, 1.5V


Would I be right in saying that the only difference between these two is that the latter has a higher maximum timing set up?

Bearing in mind Ivy Bridge will be used: when over clocking them (mostly for the lols ) - You can't change these 'maximum ' timings, only change the multipliers. Is this correct?

Additionally - would my system benefit from purchasing one of these RAM kits over the other? I'm thinking the one with the lower timings would be better but IDK.

I know one is double the cost - I'm asking about performance here and whether those numbers are actually maximum values and what their relevance is in terms of how well my system will run.

[phil4]

Maybe it's just me being dump, but I think they're identical, except the colour.

[PiMan314]

I changed the first one - put the wrong one in initially and then edited it. Now they are the same colour - the only difference is the (I think maximum) timings.

The question is basically - if I had two identical computers running side by side with the only difference being each one was running one of those kits over clocked - would one perform better?

[phil4]

Ah, you've changed the links, that make more sense now

as the numbers relate to Latency (delay), then numbers would suggest the upper kit is faster. As to what you can achieve I think this depends on the motherboard and BIOS. The bluntest tool as you suggest only allows overall frequency changes... but I think more configurable options will allow you to change timings etc.

That said, the above is what is recommended, just as with overclocking, you may not get any extra benefit if you try.

[phil4]

This may help you make sense of the numbers:
http://en.wikipedia.org/wiki/Memory_timings

[PiMan314]

That tells me some things I know (EDIT: the wikipedia link) - being that sometimes is possible to decrease clock timings to increase performance. However this guide tells me I shouldn't change the clock timings for IB and instead should change the multipliers: http://www.overclock.net/t/1247413/i...ide-at-the-end

So basically having assumed that guide offers sound information (which it may not - but until proven otherwise), I shouldn't change the clock speed - leaving me with the question: would different clock speeds (7-8-8-24 and 9-9-9-24) make any real difference when I over clock using multipliers?


EDIT: oh just saw what you added to the original post - reading that now

EDIT 2: (reply to: )

as the numbers relate to Latency (delay), then numbers would suggest the upper kit is faster. As to what you can achieve I think this depends on the motherboard and BIOS. The bluntest tool as you suggest only allows overall frequency changes... but I think more configurable options will allow you to change timings etc.

[phil4]

My undestanding is that the 7-8-8-24 is faster than the 9-9-9-24 stuff. That'll be the case whether you're running at stock freq, or have overclocked it. Likewise I know of nothing that suggests that one will overclock better or worse than the other. I think that falls to the luck side of overclocking.

So in short, my advice was and still is. Go for the lowest numbers, and or highest frequency memory.

[PiMan314]

Ok, thanks for the input!

[ik9000]

Anandtech did a big comparison of different types of RAM speeds and latencies for Sandy Bridge. The result? Provided you have at least 1600MHz Ram, there is little difference re latency.

Full test report can be found here: http://www.anandtech.com/show/4503/s...-the-best-ddr3

Unless you're benchmarking this is definitely an area where you might be able to save some money.

Edit - the links you gave one is for a single 4GB stick the other for 2x4GB. Get the 2x4GB you don't want less than 8GB in your board these days.

Also, you're better buying paired RAM than individual sticks - single sticks aren't guaranteed to be completely identical and you may therefore get problems using them in a dual channel configuration

[PiMan314]

Also, you're better buying paired RAM than individual sticks - single sticks aren't guaranteed to be completely identical and you may therefore get problems using them in a dual channel configuration

Ahhhh ok this makes sense xD

A somewhat related but also unrelated question:

I've been reading a load of reviews and comparisons on RAM and over clocking and results and I've only been taking into accounts ones using Ivy Bridge. Are RAM speeds not affected when changing between IB and SB? Basically what I'm getting at is have I been missing out on lots of good reads!?

[ik9000]

yup IB and SB RAM behaviour largely identical IIRC (for a given mobo) - both are socket 1155 chipset. overclocking IB cpu is slightly more tricky but RAM should be about the same so a comparison between RAM types in the same mobo will be useful regardless of whether the test CPU was SB or IB. Though the IB will probably deal with the more currently available RAM so a sensible place to start.

[Samwood]

So I am purchasing one of these two RAM kits:

8GB (2x4GB) Corsair DDR3 Vengeance Jet Black Low Profile, (1600), Non-ECC, CAS 7-8-8-24, XMP, 1.5V

8GB (2x4GB) Corsair DDR3 Vengeance Jet Black Low Profile, PC3-12800 (1600), Non-ECC, CAS 9-9-9-24, XMP, 1.5V


Would I be right in saying that the only difference between these two is that the latter has a higher maximum timing set up?

Bearing in mind Ivy Bridge will be used: when over clocking them (mostly for the lols ) - You can't change these 'maximum ' timings, only change the multipliers. Is this correct?

Additionally - would my system benefit from purchasing one of these RAM kits over the other? I'm thinking the one with the lower timings would be better but IDK.

I know one is double the cost - I'm asking about performance here and whether those numbers are actually maximum values and what their relevance is in terms of how well my system will run.

I just looked at both of the links and there is only £1.20 difference. The one with the CAS 7-8-8-24 timings will be very slightly quicker, but this will be barely noticeable. My advice is to just purchase any 8GB 1600Mhz kit, whichever is cheapest. There are often offers so keep an eye out.

As for overclocking, this depends on your motherboard as to what you can change. With my board (see signature), I can change all the timings and multipliers. CAS timings represent the time that the memory unit can spend searching for a specific 'chunk' of data, the frequency is how fast it can process the data throughput.
I.e. low latencies makes a system feel 'snappy' (as data is accessed quicker), and high frequencies make the processing of large amounts of data quicker (so slightly less loading times for large files).
Most people when overclocking relax (increase) the timings to gain higher frequencies.

With an IB system there aren't huge gains past 1600Mhz, its worth attempting an OC to get 1800Mhz (or 1866Mhz). But past that you will probably have to relax timings a lot which will make your system feel a bit sluggish.

[Spank]

Think you've got the links wrong as the first link is only 4GB & the 2nd is 8GB, as you will hardly notice any difference in timing go for the 8GB as it's only about £1 more expensive

[PiMan314]

@Spank
It would seem, but no - I intended those links and those RAM models, and to run 2x4GB of both 4GB card. Unbeknown to me beforehand, ik9000 pointed out that seeing as the first 4GB card is sold singularly and not as a double -

single sticks aren't guaranteed to be completely identical and you may therefore get problems using them in a dual channel configuration

@Samwood
Damn that is a sweet motherboard.... *snaps out of daydream* -

low latencies makes a system feel 'snappy' (as data is accessed quicker), and high frequencies make the processing of large amounts of data quicker (so slightly less loading times for large files).
Most people when overclocking relax (increase) the timings to gain higher frequencies.

Running some large simulation software would be considered processing large amounts of data.
If I wanted a gaming build, would it be desirable to have the low frequencies to make the system feel snappy?

I would definitely like to try OC to 1800~66~ish - I'm not sure, but I don't think the Mobo I'm looking at would support this?? (can't find any guides on how to correctly interpret the Mobo memory speed) Gigabyte GA-Z77-D3H

Anyone know about that? ^

[ik9000]

with SB and IB the max RAM speed supported natively (by the intel default spec) is 1600MHz. To get higher just adjust the mobo settings in the BIOS to increase the frequency. The user manual is downloadable from the gigabyte website and explains the steps. You can overclock right up to 2800MHz if you had RAM that would go that far. See the BIOS section of the manual. http://uk.gigabyte.com/products/prod...id=4140#manual

[ik9000]

Running some large simulation software would be considered processing large amounts of data.
If I wanted a gaming build, would it be desirable to have the low frequencies to make the system feel snappy?

when you overclock RAM beyond its native frequency you can need to relax the timings. Eg my 1600MHz RAM may well run a bit faster, but it's not been certified by the manufacturer as able to do so. I can try and push it to 1866MHz, but will probably need to increase the latency from 9-9-9-24 to say 10-10-10-27 or maybe further. It may run stably with that, or may grumble and I'd have to retreat back to 1600MHz.

If you buy 1866MHz or higher then the RAM is certified to run at those speeds without needing to drop the latency. It should just be a case of changing the bus frequency and tweaking some voltages in the BIOS. Some motherboards even offer an automated clock which does this for you. Might not get quite as far as a manual process of trial and error, but a heck of a lot quicker!