Compatibility between HP Z440 and Z640 CPU Cooling Fans

[MartinZhao]

I have a question regarding the compatibility of CPU cooling fans between the HP Z440 and Z640 workstations.

Through my observation, the motherboards of the Z440 and Z640 appear to be variants of the same base design.

However, I've noticed a key difference in their stock CPU coolers:

The Z640's cooler is smaller and seems to incorporate a cutout or clearance design to accommodate the second CPU socket on dual-processor configurations.

The Z440's cooler is larger and lacks this cutout, as it's designed only for single-processor setups.

Since I am using a single-CPU configuration in my Z640, the clearance design for the second socket is unnecessary for me. I am interested in replacing the stock Z640 cooler with the larger one from the Z440, hoping to achieve better thermal performance and potentially lower noise.

My questions are:

Is this swap physically and electrically compatible? Do the mounting mechanisms, standoffs, and the 4-pin fan header align perfectly?

Will the BIOS and system firmware correctly recognize and control the larger fan from the Z440 without throwing any errors?

Has anyone attempted this modification or has official information regarding the interchangeability of these parts?

Any insights, especially from those with hands-on experience or service manual knowledge, would be greatly appreciated.

Thank you in advance for your help!

[SmithaP]

@MartinZhao 

Thank you for reaching out! 

The Z440 CPU cooler can be physically installed on a single-CPU Z640, as the mounting points and 4-pin PWM fan header are compatible. The BIOS should recognize and control the fan without errors. While HP does not officially list this as a supported configuration, community reports indicate it works fine, and the larger cooler may provide improved thermal performance and reduced noise. We recommend verifying clearance and monitoring temperatures after installation. For official validation, please contact your nearest HP service center.

[SDH]

There is more to the story. I've been doing that for years now, and there is value in doing it both forewords and backwards:

It turns out that despite changes in the contacts at the bottom of the sockets for the Z420/Z620 versus the Z440/Z640 the stainless steel "superstructure" of the sockets is identical. Thus you can use the Z440's nice large heatsink/fan in all of those. I have not personally tested this on the Z820/Z840. So, that is backwards. Forewards: Same idea for the Z440/Z640 and the Z4 G4. Finally, the big double cooling capacity Z440 heatsink/fan fits fine and works perfectly in the Z640 as long as you stick with a single processor build.

The Z440/Z640 motherboard's CPU heatsink/fan header is 6-pin. Those for the Z420/Z620 and for the Z4 G4 are 5-pin. The pinout of pins 1-4 for all these is ground/12VDC/rotor RPM sense/PWM control from motherboard to rotor. The 5th pin in the case of the ZX20 and the ZX40 workstations is always fed by a ground jumper from pin 1 to pin 5. For the 6th pin of the Z440/Z640 there is just another short ground jumper from pin 5 to pin 6. For use of a Z440 heatsink/fan in a Z420/Z620 or any Z4 G4 running a processor drawing less than or equal to 140W max TDP you simply hang the 6th pin hole on the white fan plug end 1/8" out in space off the 5-pin header. It is easy to look at the white fan plug to see which is the pin-1 end and which is the pin-6 end... the pin-6 end has the very short jumper from pin-5.

I've even posted here in the forum on official use of that Z440 heatsink/fan by HP in the Z4 G4 for any of those workstations having a processor running at over 140W Max TDP. HP created a kit from that heatsink/fan plus a special wiring adapter that lets the white 6-pin plug work with the 5-pin CPU heatsink/fan header on the Z4 G4 motherboard. In this case the adapter has a jumper from pin-3 (RPM sense) over to pin-5. This is what HP calls the "Premium" heatsink/fan wiring. If, instead, you had a ground jumper from pin-1 to pin-5 that is called the "Performance" heatsink/fan wiring. If it is just the standard four pin wiring that is what HP calls "Mainstream". From the Z4 G4 QuickSpecs:

Official from HP for the hotter processors...

The special pin-3 to pin-5 wiring adapter can be bought from a good company in China... I have posted about that in the past too. The link, HERE, shows their adapter plus pics of the official HP adapter with the same wiring (which are impossible to find). I have official HP ones here in some of our Z4 G4 workstations plus have bought some from ModDIY... they work equally well but you can actually get the ModDIY ones.

Why the interest in that particular Z440 (749554-001) heatsink/fan? It has almost exactly double the surface area of cooling fins and 4 large instead of 3 smaller cooling heat tubes. Plus, there are a lot of Z440s being parted out for recycling so a good number of those are available on eBay, low cost, for a double cooling capacity device.

Related... I watch over cooling quite a bit for our souped-up imaging workstations. There is a special quiet optional "active" memory cooling solution (644316-001) for the single-CPU Z620 builds. The Z440 heatsink/fan fits perfectly under it. In the case of the Z440/Z640 the active memory cooling solution (748799-001) is also quiet but only can be used in the Z440, not in the Z640. The active memory cooling solution (927570-002) for the Z4 G4 also fits over the double cooling capacity Z440 heatsink/fan perfectly.

[DGroves]

To "SDH"

No, the z640/z440 coolers (and the z420/620) will not fit a z820/z840 this is due to the large fan shroud that holds all of the systems main cpu/motherboard /and ram cooling fans which requires the specific model heatsink to fit in the available space

removal of this shroud is not really practical due to it's removal will completely disrupt the whole systems cooling  from motherboard and motherboard VRM's to pci-e card cooling besides  ram cooling

if you doubt me look online for a pict of the underside of the cooling shroud it's the same for the z820/z840

it's a marvel of fans and ducting channels