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The HP Community is where owners of HP products, like you, volunteer to help each other find solutions.
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I’ve been reading the threads on the forum about upgrading the Z420 and Z620 with an E5-1680 v2 CPU.


I know the workstations need to have a newer revision motherboard with the 2013 bootblock date (dealt with a similar issue when upgrading a xw9400 but there’s a trick to fix that!).


i currently have a Z620 with an early revision motherboard and 2x E5-2643 CPUs.


i just purchased a Z420 with a 2013 bootblock.


i also bought a Z420 water cooled heatsink.


In addition to those Z workstations, I’ve got a Z800 with the liquid cooling system and a few Z220 small-form-factors.


A few questions:


The Z620 obviously has a nicer case and some additional features (ignoring the ability to upgrade to a second CPU since that won’t work with a 1600-series CPU). 


1. Is overclocking/cooling better in the Z620 than the Z420 (using liquid cooling in both)?


2. I’ve seen mention of a front case fan for the Z620. Is that an option or did they all include one? Or is it something people are hacking in? 


3. Assuming I got a Z420 with 600W power supply, should that be enough to power the overclocked E5-1680 v2, a high-end graphics card (e.g., GTX 1080), an SSD, a standard hard drive, and two optical drives?


4. Will the Z420 handle 64GB of RAM? I’ve seen different specs, some saying only 32GB.


5. Is there any chance I could get my Z800 liquid cooling system in any of the Zx20 systems including a Z820?


6. Has anyone tried a Z820 liquid cooler in one of the “lesser” systems?

HP Recommended

in reguards to your questions,


1. overclocking is not supported in any HP workstation bios, while some xeon cpu's can be overclocked via the intel XTU utility my personal opinion is that system reliability/heat issues/power consumption override any possible perfermance increase if you use this system in a work related setting.


if it's home use system then a overclock and it's possible issues is not as  important as any crash/data coruption will not cost $$$, so it's up to you  just keep in mind a overclock can double the systems power draw which over a year may cost more than just buying a faster cpu up front


2. the optional z620 case fan is REQUIRED when using dual cpu's


3. again, overclocking can double the cpu's power draw, which might push the stock 600 watt supply over the edge

a good rule of thumb is to look at the video cards hp offered with the system, note the wattage draw, and keep your card to the same wattage


4. z420 ram max size will depend on if you have a rev 1 or rev2 board




5. no the z800 cooling system is based on a diffrent cpu socket and will not mount on the zx20 systems without making/modding a new cpu mounting  hardware


6. same thing as question 5, the cpu sockets/mounting hardware is diffrent between workstation generations.


in reguards to cooling, no, the z620 is a very compact dual cpu system in a case that might actually be smaller than a z420 in total volume and when using one or two cpu's will generate more internal heat than the z420

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Lastmile 77,


I am currently running an overclocked E5-1680 v2 in a z620:


HP z620_2 (2017) (R7) > Xeon E5-1680 v2 (8-core@ 4.3GHz) / z420 Liquid Cooling / 64GB DDR3-1866 ECC Reg / Quadro P2000 5GB or (MSI Aero) GTX 1070 Ti 8GB / HP Z Turbo Drive M.2 256GB + Samsung 860 EVO 500GB + HGST 7K6000 4TB /  825W PSU / Windows 7 Prof.’l 64-bit > Focusrite Scarlett 2i4 sound interface > 2X Mackie MR824 powered monitors  > 2X Dell Ultrasharp U2715H  (2560 X 1440)
[ Passmark Rating = 6280 / CPU rating = 17178 / 2D = 819 / 3D= 12629 / Mem = 3002 / Disk = 13751 /  Single Thread Mark = 2368  [10.23.18]
[Cinebench: OpenGL= 134.68 fps / CPU= 1234 cb  [10.27.18] (OpenGL using the Quadro P2000 = 150.34)


z620_2_PT9_CPU_43x + 218.750_ GTX 1080 Ti Aero_6280_2368_10.23.18.jpg


The 4.3GHz on all 8-cores is achieved using Intel Extreme Tuning Utility, currently a previous version, The version appears to matter as XTU must have to address certain microcode.  Brian1965, the XTU champion of the E5-1680 v2 at 4.7GHz uses V. and reports that choice was made after experimentation. 


In XTU, only the multiplier and additional voltage is controllable and in z620_2, the settings are x43  (=4.3GHz) + 218.7500.  The focus of this overclocking is to improve the single-thread performance for 3D CAD.  The current Passmark average single thread mark for the E5-1680 v2 is 2116  and this configuration exceeded the original goal of 2300+.  Queite a number trial configurations  indicate that 4.3 on all cores is the limit using the z420 liquid cooler  this system.  Ths system running the browser, Explorer, and WordFerfect is comfortable at 44C and under stress- 100% on all cores has indicated up to 61C . The E5-1680 v2 is rated to 85C and as Brian1965 has worked out, with custom open loop cooling, 4.7GHz at a comfortable temperature is possible- impressive results.


The z820 liquid cooler I believe will not work in the z620 as it would not fit under the CPU shroud that includes the RAM cooling as does the z420 cooler:

z620_2 with z420 liquid cooler installed.jpg

The z420 liquid cooler in z620_2


This is not a perfect fit, but as the z420 and z620 are so similar- the principle difference being the 2nd CPU riser socket- the z420 cooler does simply plug in to the 5-pin fan header on the motherboard and appear to be controlled properly through the origninal CPU fan connection and BIOS.


I've tried other overclocking combinations for the E5-1680 v2 such as 2-cores at 4.4 and the others in a progressive reduction, but I never found a stable solution with that kind of clock speed sequence. In my attempts in this z620, th ee5-1680 v2 was only stable with all cores running at the same clock speed. 


As for power, the E5-1680 v2 is rated as a 130W CPU.  I have a z420 with an E5-1620 v2 and while that is also rated at 130W, an overclocked  8-core is logically certain to use a lot more power than a stock 4-core.  The E5-1680 v2 was an option in the z420 new.  The V2 z420 is specified as accommodating 2X 150W GPU's so the z420 at stock sppeds should  support the 1680 v2 and a GTX 1080- there are 10 z420's on Passmark using a GTX 1080, but these systems are all 4-core - E5-1820 v2, 6-cores- E5-1650, 1650 v2,  and 1660 v2, and two GTX 1080's would not be advisable in a z420 running an overclocked 8-core.  The  GTX 1080 is listed as requiring a minimum 500W PSU and the 1080 Ti requires a 600W; there are 7 z420's using the GTX 1080 Ti, including an E5-2687W v2 8C so it does work, but that means one GPU only.  I would for myself certainly be more comfortable using a z620 if the system is seeing both intense and long duration CPU and GPU activity.


The z420 will use 64GB of RAM and I have used 64GB of ECC unbuffered or registered DDR3-1866MHz .


The overclocking in the z420 and z620 seems about the same when the cooling solution is equivalent.  I  think the the links for the potential 2nd processor in the z620 make the z420 a bit better more responsive in some way, but that's subjective. I also use registered RAM in the z620 and unbuffered in the z420, and registered is a bit slower due to the one-bit parity check.


The front case fan in  the z420  appears to be dependent on the the power rating of the CPU supplied as new. IWhen I bought the z420 it had an E5-1607 v2 95W CPU, a 400W PSU, and no case fan.  When I added the 130W E5-1620 v2,  there was a BIOS error message to the effect that the front case fan was not detected.  I still had z420_2 then with an E5-1660 V2 and that had the front fan from new. I added the front fan for $20 and the 600W PSU for $50. Those are both quick plug in upgrades.


The prospects for overclocking the CPU in a V2 z420 are very good.  If I might suggest, if single-thread performance is more important than core count, consider an E5-1660 v2 6C@3.7/4.0GHz. The base clock speed and all core defualt is higher than the E5-1680 v2 (3.8GHz vs. 3,4GHz).  There is someone running an E5-1660 v2 at 4.6GHz on Passmark and the calculated Passmark single thread is about 2740- that's getting into i7-8700K gaming territory. The highest single thread performance for the 1680 v2 that I know is Brian1965 running at 4.7GHz with a large custom tower cooler and his Passmark single thread is something in the 2540  range. 


I'm extremely pleased with the results using the E5-1680 v2 in the z620 and making a very noticeable improvement with a new system would cost quite a bit- a net cost of at least +$1,500 for a couple of hundred Hz at the most.  Still, I could be quite happy with an E5-1660 v2 again.  This is the z420 / E5-1660 v2 system new in 2015, overclocked to 4.2GHz on all cores:


HP z420_2 (2015) (Rev 5) > Xeon E5-1660 v2 (6-core @ 4.2GHz)  / 32GB DDR3 -1866 ECC RAM  / Quadro P2000 (4GB) / HP Z Turbo Drive M.2 256GB AHCI + Intel 730 480GB (9SSDSC2BP480G4R5) + Western Digital Black WD1003FZEX  1TB> Creative SB X-Fi Titanium + Logitech z2300 2.1 speakers  > 600W PSU > Windows 7 Professional 64-bit > 2X Dell Ultrasharp U2715H  (2560 X 1440)
[ Passmark Rating = 5920 > CPU= 15129 / 2D= 855 / 3D= 8945 / Mem= 2906 / Disk= 8576]  [6.12.16]  Single-Thread Mark = 2322 [4.20.17]


Performance enhancement of HP zX20 series  can make these systems completely useful several years later and with better understanding of using NVMe M.2, Pascal, and now Turing GPU's, they will keep up with current workstation uses. 





HP Recommended

I have just a little to add.....


The Z420 has two power supplies, and the later part numbers one is the lower wattage..... 400W vs 600W.  No PCIe supplemental power cables on the 400W one; 2 on the 600W one.  As most know each HP part virtually always has two part numbers (Assembly P/N vs Spares P/N).  600W = 623193-001/632911-001    400W = 749552-001/749710-001.  You'd only want the HP 600W one.


Memory:  HP has old recommendation brochures from the early days of the ZX20 version 1 workstations, and then some from the early days of the ZX20 version 2 workstations, but few know there is a whole series of PDFs you should have that are even more up to date.  Here is the way to get them.... go to  HERE.


.... and download that first version PDF.  Then change the last number in this link to 2 and on up to 6 (from June 2017), and download all 6 this way.  I'd expect a 7th some day.  You'll see that HP never officially certified registered memory for the Z420.  Our friend Bambi has documented that the bit slower (pun intended) registered memory will work in the Z420 in addition to the bit faster unregistered memory that HP certifies.  The 1866 MHz memory only can be run at full speed with a 1866 rated v2 processor but it will also work fine in the older v1 ZX20 workstations (but just at the slower MHz FSB speeds of those processors).  I personally only run HP ECC registered in our Z620s and HP ECC unregistered in our Z420s.  It is interesting looking through these 6 PDFs to see how the HP certifications changed over time.  Just because HP does not certify something does not mean that it can't work.... but it may not work so I stick with these HP sheets for memory.


You mention the Z620 front case fan.... it comes in a black plastic fan holder/PCI card guide (for long cards with add-on extensions that almost none of us use).  The Assembly P/N is what you generally see on the part itself, so the black plastic is 644318-001 and the 4-wire fan is 644319-001.  Generally if you search eBay for 644318-001 you'll get the plastic and the fan as a unit.  If you don't have one in your Z620 I'd get one.... these run quite slow and quiet, and I generally add a front case fan to any HP workstation that does not have it.  You can hack these in via a Ghetto Mod but the HP setup is so cheap still that I'd only get the official kit used off eBay.  It won't be cheap forever.....


You did not mention Z420 front (PCI card cooler) case fan..... or the Z420 air flow guide.  With your Z420 v2 with an overclocked v2 processor you must add both those in my opinion.  The front PCI fan/card guide:  The Z400 and the Z420 kit is identical with part numbers 604781-001 or -003 (respectively) for the black plastic part.  Also look for the whole kit under 684024-001.  Some sellers strip out the fan (its part number is 647113-001).  It is generally a nice Nidec fan and if you search ebay under that number you may find some with the plastic and fan together for cheap.  This is a mishmash of numbers but worth the search.  The fan is 4-wire with white plug (HP PWM case fan type plug, not the more common PWM shape, both of which are 4-pin).


Front memory airflow guide:  AS P/N 663070-001.


Bambi mentioned "4-pin" header that the Z420/Z620 motherboard has for the heatsink/liquid cooling fan lead to plug into..... he meant "5-pin" header.  I have yet to get ahold of a Z420 liquid cooler to open up and figure out its wiring.... I'm assuming pump and fan all run off the single 5-pin header that a non-liquid heatsink/fan plugs into.  I have yet to see if my eBay bigger Z440/Z640 heatsink/fan will fit under the Z620's shroud..... more on that later.


The Z420/Z620 motherboards are very similar, almost identical, but with enough minor differences that they certainly cannot be swapped between the two HP cases.





HP Recommended

Thanks so much for all the info!


The Z420 has not arrived yet but I think I can see PCIe card power connections in the photo. Hopefully I’m right and it’s got the 600W power supply. Thanks for mentioning the from PCI fan because I don’t see that. I’ll need to buy one.



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Double post....

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Happy to help.... go look up in eBay 647113-001 and for 15.00 you'll find the kit for that, free shipping.


Best price on the airflow guide will be 30.00.


The 400W power supply is easy to recognize from the outside rear of the case.... grill looks very different from the 600W one.

HP Recommended

I've posted in here about building up a v1-to-v2 project Z620, and our friend Bambi has helped on some processor choices and Brian has helped with his overclocking tutorial.  Here is a little discovery that might be of interest to some of us.  Note that this is not the final build which is several weeks away.  You will be able to see the images once a moderator has released them.


After doing appropriate research and finding that the heatsink/fan attachment dimensions are equivalent between the socket used in the ZX20 and the different socket used in the ZX40 workstations I bought a Z440/Z640 heatsink/fan off eBay for about 25.00 a while back and it looked big, and had a 6 pin plug end I posted on here recently.... it's plug is different than the normal 5-pin plug for the heatsink we've become used to seeing on recent generation HP workstations for the "Performance" heatsinks/fans.  Short story.... it is big, fits perfectly and works great after changing the white plug end to a Z620 type.


The stock Z420/Z620 heatsink/fan the same, a "Performance" type, with 40 92x45mm cooling plates and 3 heat tubes.  This stock Z440/Z640 heatsink/fan is also the same for both of those workstations and also is a "Performance" type..... with 54 133x45mm cooling plates and 4 heat tubes.  The fans for each are the same size, 92x25mm, 0.4A current draw.  The wiring at the plug end is different, but I did a simple mod to covert it back to the standard ZX00/ZX20 Performance wiring I've posted on in the past (4 wires in the cable, 5 pins used:  ground, 12vdc, rpm signals back to motherboard, motherboard PWM control out to the motor PWM, and a ground jumper from pin 1 to 5).  A picture of the details is below.  The proper 5-pin white plug blanks are  what HP uses and I got them from Mouser.com.  The brass head tapered tip tool to release the thin little metal tab inside each plug socket is shown, as is a blade used to elevate that tiny tab very gently back up after you bent it down so it can again lock in place when pushed back into its respective plug socket.  Don't lose track of the proper sequence of wires.  I cut off the extra ground jumper from pin 5 to 6 that makes the new wiring different for the ZX40 6-socket plug end.  This all makes sense once you can look at it.  I noted that when screwing down the 4 heatsink screws you need to be careful that they all engage the socket's threads early on.... you need to push down on the screws against their respective springs a bit to ensure that happens.

Tools usedTools usedMouser source for 5-pin plug endMouser source for 5-pin plug endSmall originalSmall originalBig new one... almost double surface areaBig new one... almost double surface areaFits perfectly......Fits perfectly......



Here is the amazing thing... .this big guy fits perfectly in place and the black plastic shroud snaps back down into place with no binding, and with just enough space to slide a Post-It note beneath the black plastic of the shroud, and the top of the heatsink black metal.


Performance:  1714 square centimeters of the stock Z420/Z620 Performance heatsink/fan becomes 3232 square centimeters of surface area for this new one.  That is almost a doubling of cooling surface area in the same space.  Both fans use 0.4 amps.  Using the newest HP Performance Advisor below are the sensors results for the same Z620 before/after the transplant.  Nothing else was changed:

Z620 v1 stock hs f HP PA.jpgZ620 v1 Z640 hs f HP PA.jpg

The take home message is that this mod works well.... with the new Z440/Z640 heatsink/fan in place in the Z620 the CPU heatsink's fan speed is now about 60 RPM  lower (570 RPM instead of 632 RPM) and despite that the processor's temp also is now significantly lower (40 degrees C instead of 46).  I'm guessing that HP is using nearly the same motherboard dimenstions and airflow guide in these two workstations.  Many of us don't run our Z620s with the riser and two processors.  This mod will be of interest to those on the edge.  I wonder how this compares to using the Z420's liquid cooler in terms of processor cooling?  A 6 degree drop is pretty good to see from a simple air cooling change.....

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Z420 arrived today, excellently packed and looking like new - but not looking like the one from the eBay auction. 🤬


Lower-end (of the already low-end) Quadro graphics card, generic sound card instead of whatever 5.1 plus optical out card was shown in the pictures and... 2011 bootblock date mothetboard!!!


Requested a refund and will have to re-evaluate trying to find a proper Z420 or just buying a newer motherboard for the Z620. I was thinking my Z620 would be easier to sell whole rather than trying to sell an early revision motherboard, the second CPU riser, CPUs, and RAM.


The liquid cooling module and Z420 front fan assembly arrived too. The cooler is pretty cool looking. 😉


I had ordered 4x 8 GB Reg ECC RAM from eBay but ended up canceling the sale. Didn’t start out looking for HP RAM but once I saw it going for the typical price I’ve been focused on it. I noticed that some of the sellers have pictures of RAM with plain black and white HP labels on it. Others have what at least look like holographic labels. Are the black and white labels likely fakes? I bought four sticks of what looked like “real” HP RAM and the seller contacted me to say he was out of “Genuine HP” RAM and wouldn’t have any for three weeks but could sell me “Certified HP” RAM for 10% off. I turned it down and said I’d look elsewhere.


Decided to go with a 1660v2 that I got for $170 shipped. More cores would be nice but 1680v2s are going for an additional $130+ and I’ll probably benefit more from the higher single-core speed. My main use for more cores would be video encoding but these days I’m not running my Blu-ray rips through Handbrake anymore. 


In addition to the HP project, I’ve been delidding X56xx Xeons for some 2009 Mac Pros (dual processor model used delidded CPUs). Used the vise method to pop the integrated heatspreaders off but damaged one CPU (luckily only $30). Now I’ve got to get all the solder cleaned off the dies.


Has anyone gone as far as running a 16x0v2 delidded in a Zx20?



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oem ram modules can use a plain paper type label or the more expensive multi color type label,  what counts is what is printed on the label itself HP black and white labels will still have a HP part number marking on it this type of ram is only found in systems that came with pre installed memory  and is not sold for upgrades or retail sales as far as i know


the HP multicolor ram labels are "option" type ram,...... IE- ram bought after the system is bought or ram that is bought directly from HP as a retail purchase


i suppose it's possible for a seller on ebay to make fake black and white ram labels, but i've never seen one as there is little incentive for a seller to do so


there is little reasion to delid a cpu for a HP system, the only reason you had to do this for some mac pro models was due to a hight problem with the mac pro coolers if the metal lid was not removed

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