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HP Recommended
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I am considering an upgrade from my current Z620 to a Z840 system. My goal for this system is to build it up over the next year to be a virtualization server. Thus I want to get higher end processors and memory configurations. I don't need a lot in the way of graphics as it will primarily be used headless as I'll be remotely interacting with the various VMs running on it.


Having said that I am considering buying either an empty (i.e. no processors, memory, storage, GPU, etc.) or an entry level configuration. I want to utilize v4 processors and want to ensure what I buy will support v4 processors. My current Z620 is unable to utilize the v2 processors despite the Z620 specifications showing they're supported. Apparently there are two revisions to the logic board and my Z620 is the earlier board which does not support the latest processors (HP, it would be nice if you would make note of this). In an effort to avoid this with the Z840 system I think it would be wise to purchase one that already has a v4 processor installed.


EDIT: Just picked up the processors for $275 each, decided to accelerate their purchase as they were on sale, down from $300 each from last week.


In order to minimize my overall costs I was thinking of buying a single processor system and later I would purchase higher end processors to install (I don't want to spend the upfront money on buying a higher end system). By doing this I wouldn't be paying for a processor which I intend to replace. The same for memory, I don't want to buy 64GB of memory knowing that I will, eventually, be replacing those modules with higher capacity modules. Adding a second processor appears to be straightforward I just need the processor, heatsink, and fan kit. However, I'm unsure if that's all that's necessary. Likewise, it might be just as cost effective to buy a dual processor system to get the heatsink, fan kit, and peace of mind knowing it's already setup for dual processors (really leery of HP base on the logic board issue). Am I correct in all that's needed to add a second processor is the processor, heatsink, and fan kit?

Now on to power supplies. It's been my experience that single processor systems may be equipped with a lower wattage power supply (say, 875 watts) whereas dual processor systems ship with a higher wattage power supply (say 1125 watts). Does the Z840 only have one wattage power supply? Or do I need to be aware of different wattage power supplies? Ideally, I want the larger power supply even though I do not intend to use high end GPUs with it (but want to be able to utilize them if that should change).

Anything else I should factor in when considering which system to purchase?

HP Recommended

The HP Z840 supports dual Intel Xeon E5-2600v3 and E5-2600v4 series


the z840/640/440 (and the z240) only had one motherboard revision unlike the earlier z820/620 (and z800) systems


any "z" x40 workstation will run v4 cpu's  although the lower end systems may not be able to use some v4 cpu's due to power or thermal limits 

note that the z240 is a different family and uses 12xx v5/v6 xeons not the 2600 series


HP lists which cpu's they tested on which system in their model "quickspecs" which does get revised by HP so look for a quickspec with the latest date, which is usually the one posted on the HP site.






just keep in mind that there were/are cpu's that were not tested by HP which also work such as OEM model cpu's and cpu's that were not released at the time HP was testing v4 cpu's i do not recommend any engineering  "S" spec cpu's stay with final released to public spec cpu revisions


next, the z840 has two power supplies available the stock 850 watt and the upgraded 1125 watt unit


depending on the hardware you use/install you might need the upgraded supply


also the high wattage cpu's  (135 watts or more) require the "Performance" heatsinks and the 160 watt cpu requires the water cooled or vapor chamber heatsinks


it's usually much cheaper to buy a system that already has the second cpu/heatsink and upgraded power supply  as upgrading later requires discarding the existing cpu (and possibly ram) and then buying a sec heatsink two new cpu's and ram that matches the new cpu's bus speed (higher end cpu's may have a faster memory bus) and buying a upgraded z840 power supply can range from how much!!? to OMG!!!



Slot 3: Gen3 x8 - Available ONLY when 2nd processor is installed
Slot 4: Gen3 x16 - Available ONLY when 2nd processor is installed
Slot 5: PCIe Gen2 x4 when 1 CPU is installed. Transforms to PCIe Gen3 x8 when 2nd CPU is installed


a  used system should also come with all 4 hotswap drive tray brackets


for "VM" usage, RAM and core count is what you want cpu speed is a distant third

HP Recommended

Thank you very much for this information D, especially the information regarding the heatsinks, I was unaware of that.


The configuration I ultimately want to build is a dual Intel Xeon Broadwell E5-2699 v4 (22 core, 145W) system and, eventually, 1TB (or even 2 at some point, just for the cool factor). The initial configuration will be much more modest. As such I want to buy an initial configuration which reduces the number of components which will have to be replaced as I build it up. It appears I can get away with using the performance heatsinks with the E5-2699 v4?


I am currently considering a dual Xeon Broadwell E5-2630V4 (10 core, 85W) systems with 32GB of RAM. I do not know the RAM configuration (i.e. 1 x 32GB, 2 x 16GB, or 4 x 8GB) but I have a Z440 which I believe can use this RAM once removed from the Z840. I also don't know the power supply model so I'll check n that before I buy. I suspect the heatsinks would need upgraded as the current CPUs are 85 watts. How can I tell the "standard" heatsink from the performance heatsink? I assume it has a different part number but is there a visual way to tell?

HP Recommended

some things to keep in mind


high-end parts are still expensive in the used market and usually stay so as the availability pool keeps getting smaller


as such you will not save much money buying a used high end part later rather now on ebay


2. buying a used z840 with a E5-2699 v4 will get you a correct heatsink and most likely a upgraded pwr supply compare this price with your low end cpu/850 watt supply, now check ebay and see what current prices are to buy the barts to match the used pre configured high end system,.......you might be surprised


the heatsink(s) you want are these


part# 749598-001 (up to 120 watts)


vapor chamber: part# N3R54AA (all cpu's) very quiet operation will cause lower fan rpm's  compared to the normal one above


yes ram from the z440 can be used but depending on the z840 cpu installed used faster ram may be supported

HP Recommended

Thanks once again D. I have a couple of options that I am considering.


Option 1: An entry level dual v3 configuration for a under $500. I've verified the system in question has the necessary heat sinks and the 1125-watt power supply. It comes with a few extra things which I would find useful. I would then build this up. Ebay pricing on E5-2699v4 processors are $300 each so in total I will have spent $1,100 (ignoring RAM and disk space as I have plenty of SATA drives and a few Z-Turbo drives which I'll use).


Option 2: A pre-built dual E5-2699v4 system for $1,300. It comes with twice the RAM and also a 1TB SATA HD. However, it lacks the other useful things found in the first option.


Assuming the v3 system can utilize v4 processors, which I believe is possible as you mentioned there was only one revision of the logic board for the Z840 system, I think I'll go with option one and build it up. The only benefit I see to option two is that it is already built, at least processor wise, the way I want. But swapping processors isn't difficult so building a lower spec system the way I want isn't a problem for me.



HP Recommended

After doing some additional research on the v4 system decided to move forward with the v3 system. It was $399.00 for a dual E5-2620 v3, 16GB (2 x 8GB), 500GB SSD, DVD and M-Drives (two different drives), a media card reader, and three HD caddies.


As previously mentioned I verified with the seller it has the 1125-watt power supply along with the 749598-001 heat sinks so it should be good to go for the higher end processors. I'll pick up a couple of E5-2699V4 CPUs for $600 and I'm ahead $300.

HP Recommended

I hope your memory is rated to at least 2400, because that is the max memory speed that your proposed future v4 processors can run at. If your max memory speed is slower than 2400 then your proposed new processors will downshift to run at that slower speed also. The stated v3 processors your box will come with can only run at up to 1866 MHz max so whatever is in there as memory now could also only run at 1866 max currently. You can't make slow memory run faster with a faster processor, and the converse is true also.


Ideally you want either the memory's max speed or the processor's max speed to not hold back the potential overall performance.

HP Recommended

Since my plan is to replace the existing memory with higher capacity modules I wasn't concerned about the existing memory speed. I'll definitely be keeping that in mind when I purchase the new modules.

HP Recommended

I received my new system on Saturday and I must say that I am very impressed with it. The only issue is some scratching on the non-removable metal side panel (which was noted in the listing). Otherwise it's in clean condition and everything is what I expected. I'm surprised at what I was able to buy for the price paid.


The next step is to purchase 256GB (4 x 64GB, I can't locate 128GB modules on Ebay and I'm afraid to see what they'd cost from a reseller) as I want to configure it to at least what I have in my Z620 (192GB). Thinking of the quad Z-Turbo drive as the drive itself is around $200 on Ebay. And finally, for the time being, the E5-2699v4 processors (which I can now pick up for $283 each).


Thanks everyone for your assistance, it was very helpful.

† The opinions expressed above are the personal opinions of the authors, not of HP. By using this site, you accept the <a href="https://www8.hp.com/us/en/terms-of-use.html" class="udrlinesmall">Terms of Use</a> and <a href="/t5/custom/page/page-id/hp.rulespage" class="udrlinesmall"> Rules of Participation</a>.