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We have a server (ProLiant DL585 G1 by HP), which hosts Windows 2003 x64 R2 with SQL Server 2005 x64 and a host of other apps.

It currently has 6GB of RAM. We are currently very memory constrained and it's clear that we need to get more memory. 8GB will probably do the trick, however, we are not sure as to what memory configuration will give us the biggest performance buck.

Currently all 8 memory slots are filled (4 slots have 1GB chip, while the other 4 slots have 512MB chips). Should we throw the 512MB sticks away and just replace them all with 1GB sticks?

If we decided to go with a higher memory configuration (e.g. 10GB or 12GB or 16GB), is it advisable to keep all the sticks of the same size or it does not matter?

I was once told that interleaved memory requires (for better performance) that memory should be in multiples (e.g. 2 or 4 or 8 or 16, etc...). I am not even sure that the server has an interleaved configuration (and don't know how to find out), but is this true?

Thanks.

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6 Answers 6

up vote 5 down vote accepted
  1. Keep your existing memory. You may need it during the lifespan of the machine.
  2. On SMP-style machines, especially the ProLiant boxes, there are diagrams of the memory slots on the internal side of the lift-off cover. Usually there is a suggestion there if memory interleaving is needed
  3. While you can get away with non-interleaved style installation, I usually stick with it just for symmetry. It also allows you to set any BIOS settings to enable interleaved memory access.
  4. You did check your BIOS settings before placing it into production, and recorded their settings, didn't you? Otherwise, you'll need to reboot your machine to get into the BIOS to determine if there is interleaved memory support on the mobo.
  5. Try to buy your memory in pairs. Just trust me on this - you'll have less grief when you have paired memory, especially in a server that has separate memory banks that are unified by the mobo's chipset.
  6. The answer in no. 5 is meant to be more of a "better safe than sorry" answer, rather than a "cargo cult" answer. Why chance it, and with memory prices at reasonable levels at this point in time, why bother? Stick with pairs of matched memory, or if you don't want to buy sets of sticks together, get multiples of two for the same type of stick.
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I would recommend going to Crucial (http://www.crucial.com), entering the make and model of your machine, and finding out how to max your machine out.

I use that as my primary memory-upgrading resource :-)

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Currently (and this is all temporary, of course) - it seems that 2Gb sticks are the most cost effective, US$10/Gb, that's what I buy now for everything - so if you want 8Gb - purchase 2 x (2x2Gb Sets) - that would cost you around US$80 - US$100. And, if you want more memory in the future, you're not forced to throw out 1Gb sticks to free up space in your 8 - Slot Mobo.

UPDATE: I was quoting desktop RAM, I just looked up RAM for (as an example) DELL PowerEdge 1425 SC - This is US$90/2Gb - so $45/Gb in US$. THANK YOU to Farseeker who set me straight.

The RAM specs for this are: 2GB ECC Module 400Mhz DDR2-400 PC2-3200 240p DIMM, ECC, Registered, 1.8v

Quote from: www.dealram.com

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That cheap for FBDIMMs?? Damn we're getting ripped off in Australia, it's upwards of $90/gb for xeon machines! –  Mark Henderson Jun 18 '09 at 20:50
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I would use all the same brand and size. Faster memory is more important then more memory IMO.

What indication was there that you are maxed out?

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HP are pretty good with their server specs being available on the net:

HP ProLiant DL585 G1 Memory Configuration with examples

Looks like the memory on the DL585 is a bit fiddly, and dependent on which processor board you have, and you should have 8 slots per memory bank (sure you only got 4?).

With approximate costs for the HP 2700Mhz sticks of about:

2 x 512MB = £90

2 x 1GB = £130

2 x 2GB = £660

Best bang for the buck would be to populate the rest of bank 1 out with the 1GB modules to bring it up to 10GB.

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The Question was answered some time ago, but have a look at the specs for Your system if You experience degraded performance:

333 MHz memory performance requires no more than 6 PC2700 DIMMs per processor board; any more will result in the memory slowing down to 266 MHz

Have a look at this link, which should be the memory upgrade manual by HP for Your server.

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