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Posts: 22
Member Since: ‎01-18-2014
Message 1 of 3 (486 Views)

HP Z800 RAM - single rank versus dual rank?

(Cross-posted from the Desktops forum on an Expert's recommendation)




I have an HP Z800 workstation with 16Gb ram, and I want to up that to 48Gb.


This helpful document on the HP site - HP Z800 Memory Configuration and Optimization -  states:


* The HP Z800 supports Unbuffered 1GB single rank and 2GB dual rank PC3-10600E 1333MHZ ECC DIMMs
* The HP Z800 supports Registered 4GB and 8GB dual rank PC3-10600R and PC3-10600P 1333MHz DIMMs


But the data sheet


( )


for the currently installed  RAM  - (four times 4Gb sticks, Samsung Part # m393B5270dh0-yh9) , says this is 4Gb single-rank -


What I understand from some reading is that single-rank might have some small latency advantage due to the lack of the ranking buffer.  And apparently the Z800 can support it since that's what's in there - it doesn't have to be dual rank as the HP doc says. (Or maybe saying it supportds dual rank implies it can also support single-rank?)


So - I'm shopping for additional 4Gb sticks - I know I should not mix single and dual rank.


I can find dual-rank sticks cheaper than single rank.  Tossing the existing sticks and buying 12 new dual-rank would actually be cheaper than adding 8 new single-rank.  But is there a performance advantage of the single-rank?


Do I ditch the existing and get all new double-rank 'cause it's cheaper and performs just as well, or do I shop for new single-rank and pay the premium 'cause it performs so much better?



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Posts: 22
Member Since: ‎01-18-2014
Message 2 of 3 (467 Views)

Re: HP Z800 RAM - single rank versus dual rank?

After more reading maybe I have it backwards - is dual rank actually better for this machine?

Posts: 22
Member Since: ‎01-18-2014
Message 3 of 3 (448 Views)

Re: HP Z800 RAM - single rank versus dual rank?

In the meantime - I've found the exact same sticks as already in the achine - Samsung Part # m393B5270dh0-yh9 - at a good price - better than the dual-rank.  So now I'm hoping the single-rank is actually better - or at least close to equivalent - in terms of performance.  If it matters, the Z800 is being used for music and video editing, and I'll be going 48Gb in 12 x 4Gb.


Same part #, same Samsung sticker on the stick - just not an HP branding sticker - but I'm guessing they all just stick their stickers to the same stick from Samsung.

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