Fastest ram for z420 ?

[alexanderhernan]

What is the fastest ram supported in the HP z420 ?

[DGroves]

Max speed is 14900R, assuming the required CPU is installed

Memory will operate at the speed of the slowest rated installed processor or DIMM

not all z420 cpu's support 14900R speeds,

if you use a cpu with a slower speed the memory will run at  1600, 1333, or 1066mhz

[alexanderhernan]

Okay, but the fastest ram will work with a slower spec CPU right Z?

The ram will just down clock to the slower speed automatically ?

[DGroves]

which part of the statement below is giving you trouble?

"Memory will operate at the speed of the slowest rated installed processor or DIMM"

[alexanderhernan]

Should I use regular 5v ram or ( -L ) low voltage ram ? 

[DGroves]

first of all you can't buy 5v ddr3 dimms..................................................

next you need to spend time reading the information HP has provided for the z420, we are not here to answer questions easily found in the provided HP documentation.

https://support.hp.com/us-en/document/c03277050

http://ntsizing.external.hp.com/drvlib/docs/Z420_Memory_Configurations.pdf

www.crucial.com

https://www.crucial.com/compatible-upgrade-for/hp---compaq/hp-z420-workstation

the HP "quickspecs" state the compatible ram specs

https://support.hp.com/us-en/document/c03277050#AbT2

[SDH]

The answer to your original question is that it depends, as DGroves indicates.  You need to discover the search feature of this forum.  Learn to do that, and if you had you'd know the answers to all your questions already.

Here is a link to get more recent memory info... old HP documents will only show the info for the earlier v1 versions of the Z420/Z620 workstations.  You can look this PDF up and also can change that last ver=4 number to 1,2,3,5,6 and save each for reference:

https://www8.hp.com/h20195/v2/getpdf.aspx/c04164501.pdf?ver=4

Only the v2 versions of the ZX20 workstations can run the v2 processors, and only the fastest v2 processors hit 1866 speeds.  

I have posted in here about the fact that with proper selection of RAM you can run the same ECC buffered 1866 RAM that does fine in the Z620 v2 also in the Z420 v2.  Go find that info if you have a Z420 v2.  Otherwise it is a waste of time.  Don't ask how to tell if you have a Z420 v2... look it up here in the forum.

We recently built up now over 25 Z420 v2 boxes each running a recycled E5-1660 v2 processor, and each are running 4 sticks of the 8GB ECC buffered server memory that HP certified for the Z620 v2.  That way we can boost some of those later up to 64GB total.  All recycled server RAM... and I even included pictures of the sticks in my post to help in eBay searching.  I got some of that for as low as $11.00/stick, including shipping.

"Supported" means HP did all the time consuming expensive conformance testing in a specific workstation.  The fact that the memory we're using is not listed as supported for the Z420 (v2) in the PDF above simply means HP did not do the testing.  They won't ever update that testing but we validated it with that memory here.  Still works great for our needs... still best bang for the buck for us.