• ×
    Need Windows 11 help?
    Check documents on compatibility, FAQs, upgrade information and available fixes.Windows 11 Support Center.
  • post a message
  • ×
    Need Windows 11 help?
    Check documents on compatibility, FAQs, upgrade information and available fixes.Windows 11 Support Center.
  • post a message
Are you having hardware issues? Click here for tips and tricks.
HP Recommended
HP z620
Microsoft Windows 7 (64-bit)



While finishing a long, complex project with hundreds of pages of text and ninety complex Sketchup models, trusty HP z620_2 began to refuse to run the larger- 190MB+ models in a usable way.


Z620_2 for a long while had been running at 4.3GHz on all eight cores of a Xeon E5-1680 v2 using the Intel Extreme Tuning Utility "XTU" (v. and cooled by a z420 AIO liquid cooler:


z620_2_z420 Liquid Cooler_w Shroud_7.3.17.jpg

Obviously, the z420 cooler was not designed to work with the z620 memory cooling shroud, but as the motherboards of z420's and z620''s are virtually identical, it worked.


 The Passmark single thread mark "STM" of z620_2 / E5-1680 v2 was 2368:


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


The average Passmark STM for the 1680 is 2,075


The 3D modeling capabilities are related to the single thread performance while the ray tracing rendering (VRay) performance is related to the number of cores . Since renderings can be set up to run in a queue on z420_3, z620_2 could be set up to focus on fast 3D CAD navigation and regens.


A Xeon E5-1650 v2 was purchased for $50  and installed with the z420 liquid cooler.


CPU's with fewer cores run cooler and when overclocked may run at higher clock speeds without exceeding the power limits.


With experimentation,  z620 v2_E5-1650 v2 could run on all cores at 4.7GHz  (47X + :


z620_2_47x + 238.281_Passmark ALL= 6485_STM=2606_8.9.21.jpg

This may provide z620_2  with among the highest STM- 2,606 of any z620. Of the 667 E5-1650 v2 systems on Passmark, z620_2 is rated No 3.


The same experiment was done, installing a Xeon E5-1650 v2 in z420_2. This  did very well also. At 4.6GHz:


z620_2_4.6_46x + 203.125_3X Fans_Passmark ALL Tests_6378_STM 2549_8.7.21.jpg

The goal was to have a system with an STM of 2,500.  I'm considering installing the E5-1680 v2 in z420_3 and running at perhaps 4.3 or 4.4GHz.  By the way, the 1680 v2 will run all cores regardless of the overclock at 3.4GHz.


In both z620_2 and z420_3, attention was given to the cooling by adding supplemental fans, 2X 70mm in z620_2:


For the experiments, two HP 70mm fans were simply taped to the z620 shroud. An inexpensive ($13) eight-channel 3-pin/4-pin fan controller was installed in PCIe SLOT 1 and is powered by a male to female Molex cable.  The front 70mm fan needed a 3/4-pin cable extension:

z620_2_z420 Liquid Cooler w 2X Aux Fans_SM_10.24.21.jpg


The rear auxiliary fan:

z620_2_z420 Liquid Cooler w 2X Aux Fans_Rear_Contlr_10.24.21.jpg

The nice feature of the controller is that the connections are paired and each each pair has a separate speed control:


z620_2_z420 Liquid Cooler w 2X Aux Fans__Contlr_10.24.21.jpg

A similar arrangement was done in z420_3

Temperatures are quite good in z620_2. Notice all cores are running at 4.7GHz:


z620_2_47x + 238.281_Temps_Idle after Passmark ALL_STM=2606_8.9.21.jpg

More fans may be added. A couple of the 70mm fans for some reason have some bearing noise and will be changed for quiet-rated fans and then the installation will be made permanent, probably by making a  narrow-sided open square plate of 2mm ABS with threaded mounting holes.


A long post as usual, but may be useful to those of us either waiting for new systems or components to be available at realistic prices or have zX20 v2 systems that can be raised close enough to a comfortable performance level.




HP Recommended



Good news on the added cooling,  It looks to me like you were able to fit in two cooling fans in a push from front-pull to back configuration.  Might you be getting a bit low on internal fluid in your Z420 liquid cooler?  There is the internal access port screw reached from inside above the sealed impeller chamber that allows access to add fluid as needed.


We like the Noctua SSO2 bearings for quiet fans... but I don't think Noctua makes a 70mm thin fan:

SSO2 Bearing (noctua.at)


A trick I have learned with HP hard black plastic parts... bonding with Gorilla brand "super glue" works very well.  They make a gel and a liquid version of that, and it is easier to work with gel (small tubes give best control).  It seems to literally chemically fuse a very thin outer layer of the plastic to what you want to "weld" it to. 


eBay and McMaster.com have nice options of pre-made fiberglass plate in many dimensions, and you could weld two cross piece of that, predrilled for the 2 upper and 2 lower fan attachments at the front and rear openings of your memory cooling fan saddle with the liquid cooler beneath.  During glue setup I run a fan across the work area to keep the fumes from slightly frosting the adjacent plastic parts. 


For fan attachments we use the elastomeric Noctua rubberized devices that are pull-through and provide significant vibration reduction.  I'd be happy to send you a set for both fans.

HP Recommended



I appreciate the reply, especially the remark concerning the liquid cooler refill. Could you a word more about the location of that refill port? 


While it quite easy to sort of tape things together for proof of concept the details were a bit fussy; for example cable selection from the eighty thousand choices. Fans too are fussy and I think I already have about two sets  as the original plan was to modify the z620 shroud by cutting away the horizontal, lateral stiffening plates so there could be two push and two pull fans.I bought a spare z620 shroud ($20) and a Dremel tool for that project.


That may still happen as I have the fans, but It's perturbing that the actual HP fans are too noisy to run at even moderately higher speeds. I would be pleased to buy Noctua as far as I know, they are very quiet, but the firm is not offering 70mm. There are however silent 70mm fans by Gelid , Startech, and Nexus. The z420_3 arrangement uses a pair of 60mm in the pull position with a single 80mm for push.  That had an odd problem as the 80mm push fan is in a static pressure condition such that the air stream bounce off the AIO radiator fan. I think it is nearly nulling the  air flow.  I've experimented with the position in case the problem is a proximity factor but so far I'm not sure how static pressure problems are solved.


Workstations are interesting in that they tend to be so particularly designed in such detail that modificationts are limited.  Consider how few Xeon CPU's  may be overclocked.



† 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>.