Memory interleaving?


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Message 688813 - Posted: 5 Dec 2007, 0:34:39 UTC

I am building dedicated SETI units, with minimal memory. I understand the amount of memory is not critical if the unit is only running SETI. Would it be better to split the memory into two modules for interveaving purposes, and would this decrease latency?
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Message 688820 - Posted: 5 Dec 2007, 1:01:53 UTC
Last modified: 5 Dec 2007, 1:07:14 UTC

Most modern boards are interleaved for memory these days, so there is no need to. I'm not sure if it decreases latency, but it does increase mem bandwidth.

I'm no expert so I will differ to more knowledgable sources on this forum...

[edit} One stick of ram is better than 2, generally speaking if I re-read that correctly.

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Message 688832 - Posted: 5 Dec 2007, 1:33:32 UTC
Last modified: 5 Dec 2007, 1:33:56 UTC

Many folks have looked at this and compared with & without.
General consensus is that you get expect interleaving to give you a noticeable boost in WU processing speed and therefore higher RAC on C2D & Quad Core.
On 2-socket Xeons and Mac Pros, it's has even greater impact.
So, you want at least dual channel configuration if possible.

Memory is pretty cheap today. You can get 2x1GB DDR2-667 or 800 for less than $30.00 w/ rebates etc. ATM if you're willing to shop around.

Good luck!
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Message 688900 - Posted: 5 Dec 2007, 9:05:24 UTC - in response to Message 688820.

[edit} One stick of ram is better than 2, generally speaking if I re-read that correctly.


No, 4 sticks is better than 2, is better than 1.

How can one achieve interleaving (parallelism) with 1 stick?

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Message 688923 - Posted: 5 Dec 2007, 12:30:13 UTC - in response to Message 688900.

How can one achieve interleaving (parallelism) with 1 stick?

Some support that...

(Multiple RAM chips on the one DIMM.)

What you don't get is "Dual Channel operation", but then again that didn't exist in the era of 200 MHz CPUs for PCs.

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Message 688927 - Posted: 5 Dec 2007, 13:16:07 UTC - in response to Message 688900.

[edit} One stick of ram is better than 2, generally speaking if I re-read that correctly.


No, 4 sticks is better than 2, is better than 1.

How can one achieve interleaving (parallelism) with 1 stick?


I was referring to using a 1gb stick instead of 2x512mb sticks. My old Athlon t bird ran on a gigabyte via chipset board that only had 2 way enabled. After I used used a mod by George Breese ( http://www.georgebreese.com/net/software/readmes/venabler_v015_readme.htm ), 4 way was enabled and made a significant difference.

But again, unless I'm wrong modern boards are already enabled.

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Message 688983 - Posted: 5 Dec 2007, 19:34:33 UTC

I've read that two sticks (properly matched and mounted) are better (and required) than one stick for dual-channel memory. Of course some motherboards don't even provide dual-channel in the first place but maybe things are better now than when this stuff was discussed about two years ago.
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Message 689500 - Posted: 8 Dec 2007, 1:24:36 UTC

Thanks for all the info, have ordered another 512MB!
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Message 689548 - Posted: 8 Dec 2007, 2:14:21 UTC

The trick is they are matched... a bit pricier, but worth it depending on the rig. But, you have to buy them 'matched'.

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Message 689741 - Posted: 8 Dec 2007, 14:07:08 UTC - in response to Message 689548.
Last modified: 8 Dec 2007, 14:09:23 UTC

The trick is they are matched... a bit pricier, but worth it depending on the rig. But, you have to buy them 'matched'.

I've never needed to use 'matched' DIMMs in any PC. If the DIMMs run to spec and have the same timings spec, then any from anywhere will work fine. If you do use DIMMs with differing timings specs, then place them in the slots so that the slowest gets interrogated for it's SPD settings, or just set the timings manually.

Easiest is to get whatever multiple DIMMs of the same spec. No need for any additional 'matching' beyond that.

The only time you might want RAM that are all of the same batch is if you're going to play at OC-ing and you'd want them to fail at about the same extremes. Even then, I'm not so sure because you'll get failure for whatever is the slowest path. Perhaps its better to spend your extra money on getting faster parts in the first place.

Otherwise, it's just better to keep things clean and cool and with a balanced airflow for good cooling.


... And then there is all that (profitable) folklore generated by those Marketing scamsters...

Happy crunchin',
Martin
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