PDA

View Full Version : What's up with Intel going back to dual channel memory?


sillyeagle
12-15-11, 09:57 PM
I've read at least 5 Sandy Bridge reviews, and none of them touch on why triple channel memory is no longer offered/needed. One review did talk about improvements with pre-fetch, which makes it sound like Sandy Bridge just doesn't need as much bandwidth as Nehalem. Is that right?

I think Nehalem using triple channel has 25% more memory bandwidth than SB, but seems hard to believe pre-fetch improvements alone could lead to SB using 25% less bandwidth.

Roadhog
12-15-11, 10:13 PM
Sandy bridge has way more memory bandwidth than nehalem.

http://www.guru3d.com/article/core-i5-2500k-and-core-i7-2600k-review/18

Viral
12-15-11, 10:40 PM
Who really cares if it has less of something if it still performs better.

sillyeagle
12-15-11, 11:08 PM
Sandy bridge has way more memory bandwidth than nehalem.

http://www.guru3d.com/article/core-i5-2500k-and-core-i7-2600k-review/18

Hmm, well the 25% figured I saw was this:

Triple-channel Nehalem CPUs still provides around 25 per cent more throughput than Sandy Bridge, and the new CPU needs to scale all the way to 2,133MHz in order to exceed Nehalem's 1,600MHz figure.

http://www.bit-tech.net/hardware/memory/2011/01/11/the-best-memory-for-sandy-bridge/12

Given the figures you posted I'm not sure what bit tech is talking about here. Also I have yet to figure out how SB is running more bandwidth than Nehalem in the guru3d test considering they're only using 1600MHz memory with the SB rig, which I assume is what their Nehalem rig is also using.

Who really cares if it has less of something if it still performs better.

You have a problem with somebody trying to understanding the reasons why it does or does not perform better? You might enjoy just not worrying about it and remaining ignorant of such things, but I generally like to understand those things when looking at a new system.

Roadhog
12-15-11, 11:49 PM
Yeah, not sure what to tell you. I don't follow SB that much.

mullet
12-16-11, 12:02 AM
I love my dual channel mobo.

Rakeesh
12-16-11, 12:54 AM
I think the better question is, why bother with triple channel memory?

http://www.tomshardware.com/reviews/Intel-Core-i7-Nehalem,2057-13.html

Ninja Prime
12-16-11, 01:52 AM
The short answer is, most of the time, CPUs don't need huge bandwidth to RAM. Triple channel was mostly a waste when it came out, maybe on SB-E it might matter a little, but even then its single digit precentage I'm guessing.

Bah!
12-16-11, 02:24 AM
Why did they get rid of it? Because it was a useless feature that barely gave any performance increase in synthetic benchmarks and zero increase in actual use.

sillyeagle
12-16-11, 02:54 AM
Yes, thank you. I guess the guru3d results are better simply because the CPU is faster... no memory bottleneck either way. Makes sense.

Ninja Prime
12-16-11, 03:47 AM
In a multi-chip server/supercomputer board it might have more impact, so thats probably the major reason for the original inclusion.

bobkn
12-16-11, 08:16 AM
Odd that no one has mentioned:

Intel has gone to quad channel with Socket 2011, and the Sandy Bridge E processors.

http://en.wikipedia.org/wiki/LGA_2011

Q
12-16-11, 08:58 AM
$$ vs $$$

More processors sold when total system costs are cheaper.

Bman212121
12-16-11, 09:50 AM
Odd that no one has mentioned:

Intel has gone to quad channel with Socket 2011, and the Sandy Bridge E processors.

http://en.wikipedia.org/wiki/LGA_2011

Yea, which makes even less sense for the typical desktop user. Sandy Bridge E is considered a workstation / server platform, so the real advantage is in the number of DIMMS you can stick onto one board. The other thing to point out is that if you were using memory intensive programs that required ECC memory, quad channel could be useful because the modules are usually clocked slower. You might have 1333 mhz ECC modules where a desktop user could be using 1600+.

frenchy2k1
12-16-11, 12:55 PM
You are comparing platforms for two different market segments.

The successor to the workstation platform, with chips from the Nehalem/Gulftown generations, is Sandy Bridge E. Not Sandy Bridge.
SNB-E uses a quad channel interface, so Intel actually moved forward here.

The desktop platform never used Triple Channel.
Even though the i7 920 was a very successful CPU and very popular for enthusiasts, it was part of the previous workstation platform.

^ this

On top of that, they qualified higher speed memory. Nehalem was actually officially limited to 1333. SNB is rated for use with DDR3 1600. SNB-E, same, but with 4 channels.

Intel loves their market segmentation. Best way to extract the optimum amount of money from each customer (if the customer does not get too confused).

Redeemed
12-16-11, 01:17 PM
I've not used tri-channel since owning this x58- always dual channel and DDR3 1600. Well, for a brief while I was running DDR3 1333 but... :p

uOpt
12-20-11, 09:55 PM
I've read at least 5 Sandy Bridge reviews, and none of them touch on why triple channel memory is no longer offered/needed. One review did talk about improvements with pre-fetch, which makes it sound like Sandy Bridge just doesn't need as much bandwidth as Nehalem. Is that right?

I think Nehalem using triple channel has 25% more memory bandwidth than SB, but seems hard to believe pre-fetch improvements alone could lead to SB using 25% less bandwidth.

Did you ever see that translate into a real-world application performance difference?