okamon
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RAM: difference between SEC and BBC?
I am buyign some memory for my proliant server. I didn't want to buy it from hp as it's too expensive. I pulled out my existing memory and found it's actually made by samsung. and the model is M393B5673FH0-CH9Q5
I found 2 websites that are offering the model, but one is SEC and the other is BBC, whats' the difference? both of them have same M393B5673FH0-CH9Q5, btu the price is big difference.
http://www.memoryten.com/p/023190/
http://memoryx.com/m393b5673fh0-ch9q5-2gb-ddr3-1333mhz-pc3-10600-samsung-sec-rdimm-module.php
I found 2 websites that are offering the model, but one is SEC and the other is BBC, whats' the difference? both of them have same M393B5673FH0-CH9Q5, btu the price is big difference.
http://www.memoryten.com/p/023190/
http://memoryx.com/m393b5673fh0-ch9q5-2gb-ddr3-1333mhz-pc3-10600-samsung-sec-rdimm-module.php
For example:
2GB £30.99
4GB £45.99
8GB £74.99
16GB £212.99
Best price is the 8GB ones.
http://www.crucial.com/uk/store/listmodule/DDR3/list.html?gclid=CJakqrPn5q4CFQITfAodNhSnhw&cpe=pd_google_uk&ef_id=U@xOynB5QjkAAELx:20120314162816:s
2GB £30.99
4GB £45.99
8GB £74.99
16GB £212.99
Best price is the 8GB ones.
http://www.crucial.com/uk/store/listmodule/DDR3/list.html?gclid=CJakqrPn5q4CFQITfAodNhSnhw&cpe=pd_google_uk&ef_id=U@xOynB5QjkAAELx:20120314162816:s
ASKER
I have a proliant ml350 g6 with 1 cpu, 4 gb of memory (2gb x 2). I just want to have 8gb in total as it's for my lab. I did run the HP memory configurator and it suggest me to go for 2 gb each for best performance... is not true? or I get same performance if I put a one 4gb on top of my 2x2gb?
Will I run into any issue if I mix with Kingston memory?
Will I run into any issue if I mix with Kingston memory?
1 * 4GB is fine, you'd have 2GB on 2 channels and 4GB on one of them whether you added 2*2GB or 1*4GB. Best performance is got by having same amount on each channel, that would be 12GB, 2 new 4GB ones plus the current two shuffled to be on the same channel.
Models with 2 * 2GB are quite likely to have UDIMMs rather than RDIMMs and you really have to confirm that since you can't mix. If you boot SmartStart, maintenance, insight diagnostics you can get a report of exact part number.
No issues mixing makes, they're all covered by a JEDEC standard. They do have to have temperature sensors in them though (which ECC RAM does have) or the fans will go on full speed.
Models with 2 * 2GB are quite likely to have UDIMMs rather than RDIMMs and you really have to confirm that since you can't mix. If you boot SmartStart, maintenance, insight diagnostics you can get a report of exact part number.
No issues mixing makes, they're all covered by a JEDEC standard. They do have to have temperature sensors in them though (which ECC RAM does have) or the fans will go on full speed.
ECC (which is what you typically install in servers) is Error Correcting Code memory http://en.wikipedia.org/wiki/ECC_memory. It handles parity errors which can be caused by random events and fixes them.
The other RAM you were looking at was RDRAM, a product of RAMBUS and not very favored these days - it is not compatible with any other kind of RAM.
As a general rule, you want to use memory in pairs, and they should be the same spec, in order to take advantage of dual channel operation which will double the bandwidth. Mixing memory in servers is not the best approach, because you have the risk of some incompatibility.
The other RAM you were looking at was RDRAM, a product of RAMBUS and not very favored these days - it is not compatible with any other kind of RAM.
As a general rule, you want to use memory in pairs, and they should be the same spec, in order to take advantage of dual channel operation which will double the bandwidth. Mixing memory in servers is not the best approach, because you have the risk of some incompatibility.
ASKER
andyalder, I agree with Callandor that I should use memory in pair.
"4GB is fine, you'd have 2GB on 2 channels and 4GB on one of them.." if I do this then I cannot double the bandwidth
"4GB is fine, you'd have 2GB on 2 channels and 4GB on one of them.." if I do this then I cannot double the bandwidth
Not pairs on this one Callandor, it's Xeon 5500 series with 3 memory channels per CPU. The channels work independantly so you get 3*throughput of a single channel for the lower addresses however it's mixed and only loose interleaving on the but of RAM that sticks above the rest, e.g. 2*2GB + 4GB first 6GB is 3way interleaved and the last 2GB is non-interleaved. Older CPUs liked pairs, and the E5s in the very latest Intel 2P servers like quads although they'll put up with just about any mix and still perform well.
ASKER
actually my cpu is XEON E5620 2.4GHZ. Same case?
The E5620 is triple channel, but I've never heard of the split interleaving andyalder is referring to. Andy, if you can give me a link to do further reading on this, I'd appreciate it.
ASKER
Callandor, so if I put 4 x 2gb instead of 2x2gb + 1x4gb... will that degrade the performance? I know you have explained something in your previous post but I don't really get it.
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There is a very tiny performance benefit of having 2 * 2GB DIMMS in a single channel over having a 4GB one, that's down to precharge delay. It's so insignificant it's not worth considering in my opinion.
Andy,
Much appreciated. In your first reference, I saw "Always populate all 3 memory channels on each processor with equal memory capacity", under 4.0 Best Practices. Is the reason you're making your recommendation because this server doesn't have triple channel slots?
Much appreciated. In your first reference, I saw "Always populate all 3 memory channels on each processor with equal memory capacity", under 4.0 Best Practices. Is the reason you're making your recommendation because this server doesn't have triple channel slots?
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There is another option, buy a bag of 2GB DIMMs from a broker, We regularly remove the original RAM to put bigger sticks in as HP don't sell ramless servers to th general public, Must be thousands of brand new unused sticks on ebay.
Very good in-depth explanation, Andy.
Well, okamon, you've got your answer from one of the best.
Well, okamon, you've got your answer from one of the best.
No idea what BBC stands for except British Broadcasting Corporation.
It doesn't make much sense to be buying 2GB sticks these days anyway, exactly what model/generation ProLiant do you have, and what RAM is currently installed (including whether UDIMM or RDIMM, which CPU(s) and how many? What is new target amount of RAM?
From that I can give you a better spec of RAM to buy, quite likely 8GB 2rank x4 as they're well priced. Then you can get Kingston or any other equivalent from the HP part numbers.
Oh, and don't bother about the HP DDR3 memory configurator, it's OK for what it does but isn't as flexible as the CPUs/servers are so doesn't offer the best configs.