DDR3 1333 vs 1600mhz

[borals]

Hi All,

I'm currently building a i7 860 system, and I just need to know if I will see any benefits of 1600mhz RAM over 1333mhz?

I wont be overclocking and predominantly use my pc for gaming.

For someone like me, I used to be able to figure these things out with the old FSB model, but the new QPI architecture makes the decision a bit blurry for me!

Any help appreciated,

borals.

 

[n7]

Hi All,
I wont be overclocking and predominantly use my pc for gaming.

Hiya borals, welcome to the forums

If you do not OC & prefer to stay out of the BIOS [to apply the correct DRAM frequency/timings/voltage], some JEDEC default 1.5v DDR3-1333 will be suitable for you, if not preferable in some ways.

Most of the time, pricing is very similar for DDR3-1600 kits, but be aware it's more likely you'll need to visit the BIOS & manually set the frequency to DDR3-1600 to make that happen.

 

[borals]

Cheers, for the welcome and response.

I'm happy to adjust any BIOS settings and such, I do have experience.

I was more concerned say, if getting 1600mhz ram was "wasted bandwidth" so to speak.

Basically, if 1333mhz in dual channel can handle all the QPI can throw at it under normal (stock) speeds, then I'm happy with that.

So, would it?

Cheers, borals.

 

[LokutusofBorg]

The only advantage you would see is if the 1600-rated RAM can do tighter timings when run at 1333 compared to whatever 1333 RAM you would buy. Otherwise you're going to have to overclock to gain access to any of that overhead.

 

[borals]

Awesome, thanks!

 

[n7]

The only advantage you would see is if the 1600-rated RAM can do tighter timings when run at 1333 compared to whatever 1333 RAM you would buy. Otherwise you're going to have to overclock to gain access to any of that overhead.

With the i7s, you can do DDR3-1600 @ stock speeds.
For the i5, you only have DDR3-1333 @ stock.

In this review you can see higher speeds > lower speeds, even with better timings, but the difference isn't worth getting too excited over.
http://www.xbitlabs.com/articles/memory/display/ddr3-1600-lga1156.html

 

[LokutusofBorg]

With the i7s, you can do DDR3-1600 @ stock speeds.

Ah, I'm running an i7 920, and I apparently missed this (or it didn't stick in my head) when I've read about the new i7s. I thought 1333 was their fastest @ stock. Thanks.

 

[Ben90]

With the i7s, you can do DDR3-1600 @ stock speeds.
For the i5, you only have DDR3-1333 @ stock.

In this review you can see higher speeds > lower speeds, even with better timings, but the difference isn't worth getting too excited over.
http://www.xbitlabs.com/articles/memory/display/ddr3-1600-lga1156.html

DDR3-1600 is only supported in single channel mode on the 860/870
DDR3-1333 is supported in dual channel mode on any lynnfield
DDR3-1066 is the fastest speed supported by the 920

 

[borals]

ok.

Now I'm confused again. hahahahaha.

 

[Ben90]

Basically what I meant by that is if you want to keep everything "stock speeds" your going to have run your memory at DDR3-1333 as Intel states that is the highest the i860 supports in a dual channel configuration. The reality is that these processors can handle quite a bit over that which is why we see all these performance modules on the market.

Today's modern processors with huge caches do not benefit as much from having faster memory as past architectures. While the article below is based on the i920s superior memory controller, it gives a good indication of how little different RAM impact performance.

http://www.anandtech.com/memory/showdoc.aspx?i=3589&p=1

Average frame rates are up an astounding (had to make it interesting) 1% utilizing 1200 C5 over 2000 C8 while minimum frame rates improve by a ground shattering 0% when moving from 1200 C5 to 2000 C8 in single card results. In SLI operation, average frame rates improve by a familiar 1% as we crank up memory speed while minimum frame rates are 1% better when using 1200 C5 compared to 2000 C8. Obviously, the impact on actual game performance was nonexistent with any of our memory choices.

 

[n7]

DDR3-1600 is only supported in single channel mode on the 860/870
DDR3-1333 is supported in dual channel mode on any lynnfield
DDR3-1066 is the fastest speed supported by the 920

Actually, no.

Motherboard manufacturers for P55 (can't say for H55) have implemented the option for the 12x RAM ratio (2:12) for the i7s.

X58 boards can also do over DDR3-1066 @ stock as well if you apply a higher RAM ratio [than the "Intel spec" 8x].
You can do 10x/12x for X58 (DDR3-1333/1600) for X58 as well, but as i'm off to work i don't have time to go hunt down screenies.

I do have my own i7 860 screenshot to prove what i just mentioned for P55 though.

133 (stock BCLK x12) = DDR3-1600 dual channel.
And that's dual channel w/ 4 DIMMs, not just 2.

 

[Ben90]

The keywords in your post are "Intel spec". I'm aware of the processors being able to handle a range of multipliers well over their spec, but by doing this your running out of spec.

I can give my 920 up to 2.1v in bios. I can't however claim that I'm running a voltage supported by my processor.
There are hundreds of examples of the motherboard supporting things that the processor doesn't, there is a lot more to running stock than just having a 133 bclock.

Intel's official stance on DDR3-1600x2 is "at your own risk"

 

[LokutusofBorg]

OK, Ben laid it out how I had it in my head, though I was a bit cloudy so couldn't say it in so clear a way.

I bought 1066 memory for my i7 920 when I bought everything because I didn't want to run outside of spec. I also made sure to buy modules rated at 1.5v so they were JEDEC-compliant. If I bought an i7 1156 rig I would buy 1.5v 1333 memory for the same reasons. System stability is far and away the most important thing for me.

Those are simply my personal preferences. Plenty of people do "soft" overclocking like using the higher memory multiplier that n7 is talking about with perfectly stable results. I had my time as an overclocker years ago. I don't go there anymore as it just isn't worth it to me to mess with it.

 

[borals]

I see in the CPU-z info n7 posted that is shows the QPI link as 2128mhz and the NB Frequency as 2394mhz.

So I would interpret that to mean that, using his current dual channel setup he is satisfying the output of the QPI.

Being that his ram is 1600mhz, I would have thought that 1333mhz would not achieve this, giving a higher QPI link than NB Frequency, effectively causing a, albeit slight, bottle neck.

Am I making sense, or have I completely lost it, and should take up in door bowls?

 

[Ben90]

To be honest I really can't dissect that CPU-z screenshot very well. To my knowledge the i860 doesn't have a QPI interface unless its an internal connection to bridge the CPU to the PCI-e interface.

The NB frequency is basically the Uncore (l3$, random stuff that doesn't need to be on high power transistors) and operates mostly independently of the RAM. Whats confusing to me is I know Bloomfield needs at least a 2x uncoreDR ratio or else havoc follows, but Lynnfield seems to not share that trait.

Anyways I got sidetracked from what I really wanted to say. Nehalem is completely different from the FSB architecture, and there is no more worrying about FSB:RAM ratios. Just get the cheapest dual channel DDR3-1333@1.5v you can find and leave the BIOS on auto. Intel's paid engineers will work their magic, and your system will work exactly like it should, with your RAM systems running at the absolute fastest they are rated for.

 

[borals]

Well, thanks guys.


This turned out to be an enlightening discussion, needless to say I feel much more comfortable about choosing RAM.

Cheers.