In a memory muddle!

[#1]

I need to upgrade the memory on my HP Elite 8100 Core I5 and i'm struggling to "shop around" for the memory as there is simply so much information available relating to the chips to the extent I simply do not know what to type into the likes of Ebay/Amazon. My PC has Four ports with two currently used.
Is it correct to:
1) Ensure that all ports are used and the chips are balanced out across all ports?
2) Is it particularly important that all sticks exactly match each other from the same batch?
3) That the maximum this PC can handle is 16GB restricted by the processor?
This is the dmi decode information:
http://paste.pound-python.org/show/jEAaRYlhWytb58RyCn5y/
Many Thanks and Kind Regards,
plusbg.

[#2]

Perhaps this might help....
http://uk.crucial.com/gbr/en
Two boxes with options..... click on the right hand box  "scan my system" .....

[#3]

your PC has if info correct DDR3 RAM at 1333 mhz
Your Motherboard supports max of 16gig
if you add more Ram it does not matter which make you use , as long as its same as above 

[#4]

Thanks for this - so: Second Hand (I know you might cough at me but the whole PC is second hand anyway and Paypal offers 30 day protection)
and to try and keep the memory as close as can be to what i've got already, would you be as kind as to point me to a few links on Ebay and what it is exactly that I need to type into the search string on Ebay to make absolutely sure i'm buying the right thing?
Unfortunately, using Linux I'm unlikely to be able to use the software mentioned above (command line only as it's a Proxmox Cluster)
Also, is making sure the memory matches in "batch" actually that important as I can see that as an issue if I buy it used? I'm trying to get a good idea of what the cheapest price will be? Also, is it important to make sure the load is shared out across all 4 memory bays?
Thanks 🙂

[#5]

Quote from: plusbg

Unfortunately, using Linux I'm unlikely to be able to use the software mentioned above (command line only as it's a Proxmox Cluster)

"the software mentioned above"  ? ? ? ?    I posted a link to a website ... there is no software to download... the website scans your system "on-line" and will advise what memory is installed and what/how much you can fit and the type ....
Should work with linux or whatever....

[#6]

On Linux, there is a decode-dimms program (part of the i2c-tools package) that outputs a lot of detail about the RAM modules. You might need to load the eeprom kernel module before it will work.

[#7]

Thanks both of you 🙂 Shutter - sure, but with the command line, if you do have a graphical environment installed (which is not advisable of course with servers), then there'd also not be a web browser to run the program in - unless you're saying it's fully compatible with the command line? 🙂
So the questions that still remain are:
Is it correct to:
1) Ensure that all ports are used and the chips are balanced out across all ports?
2) Is it particularly important that all sticks exactly match each other from the same batch?
Any idea of prices at all or any Ebay suggestions?

Thanks ever so much for your time so far 🙂

[#8]

Your link show your memory as samsung , when you Google the part number 
http://stuccu.co.uk/s/Samsung+M378B5673FH0+CH9-MbSLsTI-Buy-Exclusive-Deals-70-OFF-Save-Big-Lowest-Pr...

[#9]

@op,
your best bet is to buy 4 new sticks of ram from the QVL list,
use another pc go to the crucial website and select the system from their part picker (the one you want to upgrade) normally all you need is the mobo details (make model and possibly version number) it will give you a list of compatible memory sticks, from that your free  to take the part  number(s) of any kit you like and then google /ebay/amazon/any other pc parts seller website for the best price, half the time I find I can buy the exact same memory from another seller for half the price that crucial is charging,
another place to try would be offtek http://www.offtek.co.uk/ same deal with regards to choosing the correct sort of ram though (pick something that is going to work with your mobo)
you could probably find another dozen or so online stores if you look around offering the same deal, however be sure you check the HP website for bios updates before you swap out the old sticks.
because of the way in which systems use ram swapping the 2 current sticks for 4 new ones would be advisable, manufacturers of ram produce kits in various sizes in order to allow you to get something that will work as intended in the quantity you require,
and yes its better to use 4 x 4 gb sticks rather than 2 x 8gb sticks or 1 x 16gb stick when all the options have the same operating speed.
iirc the 16gb limitation is based on the mobo rather than the processor since they came with a choice of either the i5 or the i7 cpu it being based on the x57 architecture and having been issued somewhere around 2010, so unless you have one that's been upgraded with a newer mobo then it probably still has the same original limitations

[#10]

Quote from: plusbg

Is it correct to: 1) Ensure that all ports are used and the chips are balanced out across all ports? 2) Is it particularly important that all sticks exactly match each other from the same batch?

Some motherboards require memory to be installed in matched pairs.  With other motherboard designs this is not necessary but performance is improved if you do.  And some motherboards don't care.
rongtw has gone to the trouble of looking this up and his reply indicates that yours is the third case and you only need to buy the right type and not exceed the maximum capacity.  Since you are so strapped for cash as to be looking at second-hand memory it seems ludicrous to suggest you should throw-out what memory you already have.  Any performance improvement you get from adding extra memory will be huge by comparison with any further improvement you might achieve by using 'balanced' memory.  So my answers to your two questions are no and no.
At work I have a computer that had a matched pair of Crucial memory cards.  At least they were matched when new, now they have become so different that the computer no longer boots with both installed in adjacent slots.  So what you achieve at day one with regard to matched memory may not last.