Solve 528: CPU requires liquid cooling system on Z420 MB

[Snoopmasta]

After building my own "maxed out" Z420 Workstation I wanted to share 2 important findings.

1st finding:

After installing the XEON E5 2687W v2 the system bootet showing the error: "528: CPU requires liquid cooling system" which can be prompted by pressing "F1" but is annoying.

What I never found online, was the exact solution I came up with.

This works for the standard air-cooler as well as the Z440 air-cooler (I used that one).

Since the mainboard wants to see a tacho-signal for the water pump on pin 5 of the fan connector I gave it exactly that.

I assumed that the board wouldn't mind seeeing the same tacho-signal that the fan on the air-cooler reports back.

Original fan pin-out: 1-GND | 2-12V+| 3-tach1| 4-PWM | 5-GND | (6-GND for Z440)

Water cooler pin-out: 1-GND | 2-12V+| 3-tach1| 4-PWM | 5-tach2

So I simply took out the bridge between pin 1 and pin 5 of the air-cooler and used this to bridge the tacho-signal from pin 3 to pin 5. The mainboard now sees two tacho-signals (the same in this case "tach1") and thinks there is a water-cooler installed. On my board (Z420 v2) this worked flawlessly and I assume it does for all boards with the same pin-layout.

Note: In the pictures you can see the connector of the Z440's bigger air-cooler with 6 pins. Just ignore the 6th pin since it is not connected on a Z420 mainboard. I just kept the pin 6-GND in place but could also have cut it out.

2nd finding:

The screw posts on the Z420 air-cooler do not have the same length as the ones on the Z440 air-cooler.

At least in my case I needed to swap them over from the smaller to the bigger one. Otherwise mounting the cooler to the CPU wouldn't have been possible since the Z440 cooler hat basically no mounting pressure whatsoever on my Z420 v2 board.

Swapping those screws over is quite easy and can be done with only a screw driver.

[SDH]

On your first technique:  ...Nice.

I've never tried to install that processor so never have seen the motherboard demand for a tachosignal from a waterpump in a Z420 come up. I believe there is an adapter from MODDIY Home Page - PC Modding, Case Mods, Custom Cables that would work. They make a number of HP fan adapters, but their web site search engine is a bit confusing. I recently bought one from them that has the fan tach signal from pin 3 split and shunted over to pin 5... it is made for shifting a double-cooling-surface-area Z440 stock heatsink/fan over for use in a Z4 G4. The net result is actually equivalent (except for $) to the official HP kit that HP uses in the Z4 G4 to allow the latest approved high wattage processors to run in that workstation (IIRC any processor rated to draw greater than 150W max TDP). It is not that the motherboard measures the wattage... BIOS may have a way to probe the processor for its max TDP value.

Regardless...the stock Z4 G4 heatsink/fan looks like a mini-me of the larger stock Z440 one. Both fit under the memory cooling "saddle" and HP's official kit is simply the Z440 stock heatsink plus a HP-made fan adapter. That adapter and the one that modDIY makes both duplicate  your wiring mod discovery. I got one from modDIY, shipped from China where they are made, sleeved. Very nice quality and they also sell them unsleeved so you can actually see the wiring if you wish. They have been an excellent source for years now, and do excellent work. So, for others, the bigger Z440 heatsink/fan is available for under 20 USD recycled via US eBay. The modDIY adapter is under 10 USD free shipping from China (expect about a 2 week ship time). Thanks for your breakthrough on this!

A prior post on the use of this type of adaptation to get tacho into the motherboard trace from pin 5 is HERE.

Be sure to look at page 2 of that link. The one you want is HP Computer CPU Fan 6 Pin Male to 5 Pin Female Cable Fan Conn Adapter - MODDIY

Be careful... there are a few from modDIY that look similar but are for different purposes, and HP even has a wrong picture in their PartSurfer listing next to the correct part number.  HP makes several different fan wiring adapters and got confused. Here's the correct HP picture and part number courtesy of modDIY:

The correct pic and part number

Regarding your second technique:

I've used that bigger Z440 heatsink/fan in our souped up Z420 workstations wired as it comes for years now but I've never had to change out the mounting screws. I think you're a bit off on that piece of advice. Note in your pic that the Z440 heatsink's processor area part of the baseplate is thicker aluminum into which the 4 bigger-diameter heat tubes are pressed. The Z420 heatsink's baseplate you show is thinner (because it has thinner heat tubes). The net thickness is greater in the Z440 baseplate than the Z420. That is why the Z440's screws have that extra offset length shown. For both types I just carefully screw down using correct crossing technique (1 turn on each screw at a time) to drop the heatsink level, to bottom out to a gentle snug torque... roughly 10 total turns each screw). Don't crank down hard. I like the original Noctua NT-H1 thermal paste, and not too much of it. It spreads very well.

What I've found over time is that the motherboard's CPU heatsink mounting holes have the same dimensions for the Z420, the Z440, and the Z4 G4. It is the pinouts inside the stainless steel socket that differ between these different families of HP workstations. As a result, I've been able to use that nice big Z440 heatsink/fan in our Z420/single-processor Z620/Z440/single-processor Z640/ and now our Z4 G4 workstations. I'm pretty sure it would also work in a single-processor Z6 G4 but have not yet tried that. I never have had to swap out the mounting screws in any of those... that is a hassle to deal with that I believe has zero benefit. However, it surely does have some risk because you're shortening your thread contact surface area at each screw by doing that... you don't want to strip those threads because that would mean needing a new motherboard.

Again, Kudos to you.

[Snoopmasta]

Hi SDH,

thanks for the huge effort to reply. Really apprechiate those infos. 🙂

In regard to the coolers. Yeah - I kind of expected a reply like yours. But since I have no other reference - I can only go from what I experienced with my system.

The distance from the cooler contact plate to the screw mounts has been identical on my Z420 and the bought Z440 model. The geometry was the same.

Note: Those pictures up there are from the www. - I didn't want to uninstall my cooler again to take the picture.

Fact is: When I tried to mount it as is, the cooler didn't even touch the thermal paste on the CPU with all screws fully tightened. With the screws from the Z420 cooler it worked fine and full load the CPU sits at 3590MHz all core - 65°C.

If this information does not apply to other cases then I'm just a bit unlucky or someone sold me a piece of non standard equipment.

Maybe there are different models of coolers or sockets in the latest production years? 

*Edit: I've just taken a picture of the stock Z420 v2 baseplate and it is different to the one above.

Oh and yes - I've installed the longer screws there to not lose them. This combination might now only fit in that other Z440 system. 😄

Anyways - thank you again for taking the time and add useful input. 🙂

[SDH]

You have done excellent work. Yes, your two "Z420" heatsinks are very different. The original one has only 2 heat tubes vs the new one just above has 3. The stock Z440 big one has 4 and each tube also is a bigger diameter.

EDIT>>> I might have a bit of the info below wrong and will try to find some old pics of the original Z420 heatsinks. Stay tuned.

Note in your original post your pic attributed to be a Z420 heatsink/fan might actually of a Z620 heatsink. The boxy black cooling part is offset towards the top if in the Z620. Same deal with a Z640... they had to do that because if one was using two processors the slide-in second "mini-motherboard" for the second processor took up so much space that they needed to shift that boxy part upwards out of the way.

eBay sellers sometimes don't get their listings right and I bet that was the source of the confusion and wrong heatsink used in your original pre-souped up Z420 build. I've even seen them post sales of xw series heatsinks as being for the Zx00 or Zx20 workstations.

I bet that has something to do with it. I'm not sure how that would affect my use of a Z440 stock big heatsink/fan in a Z620... seems to still work fine. Here's the bottom of the Z440 stock heatsink/fan:

Thicker baseplate needed...

[SDH]

I just took a quick look on eBay. The thinner baseplate one you showed in your original post with the offset cooling box actually has two different designs, but with the same exact Assembly Part Number (the number printed on the cooling box part)... one has 2 heat tubes and the other has three. That was a surprise from HP!

Go take a look, filtering for Z420 heatsink:

2 heat tubes, thin baseplate, 5 pin plug with 1-5 ground jumper, offset box = 647287-001
3 heat tubes, thin baseplate, 5 pin plug with 1-5 ground jumper, offset box also = 647287-001
4 heat tubes, thick baseplate, 6 pin plug with 1-5 and 5-6 jumpers, offset box = 749596-001 (this was advertised as a Z420 one but with that 6-hole plug end it has to be officially for a Zx40 workstation)

This is the double cooling capacity Z440 one you want... best price lowest including shipping is 15.00 USD:

4 heat tubes, thick baseplate, 6 pin plug with 1-5 and 5-6 jumpers, centered box = 749554-001

Note that you could spoof the motherboard by using this knowledge and a lesser heatsink/fan but that does not get you the processor cooling you need and want. Using the same methods with the official double-cooling-capacity 749554-001 heatsink/fan does.

For those wondering... with the 6-hole plug end of the Z440 stock heatsink/fan and a Z420/Z620 motherboard's 5-pin CPU cooler header you just hang the unneeded 6th hole out in space when you attach the plug onto the motherboard header. #6 is just another ground jumper from pin 1 originally (via pin 5) and there is room to the side of the header to just hang it off.

[Snoopmasta]

I quickly took some pictures as well.

This one I bought as Z440 cooler and the S/N fits.

But now I remember why I thought that the cutout for the heat pipes looked similar - because it does.

My cooler has a different base plate to yours.

This seems to be the same as the one in the first comparison picture and it came with the longer screws. Still only fits with the shorter ones. 

[SDH]

Thanks... I'll go take another look at my Z420 with that Z440 heatsink in place. Maybe we should call that the "big block" one.

I have one of your processors coming as of this morning, so will be able to take a close look with the thermal paste cleaned off and the stock screws all the way down as I always have done, and then add thermal paste. Those started from Intel at 2112.00 USD... now a bit over 40.00 USD eBay recycled.

I see an added memory cooler and a Noctua fan in your most recent pictures... any added tips? Do you use one of the Z420 memory cooling baffles? Are you aware that Noctua PWM fans can be slowed down so much that they don't cool well enough when they also receive the HP motherboard's PWM braking?

EDIT: The stock Z440 big heatsink/fan comes with two slightly different base plates, but same number. To me that is quite different from the 2 vs 3 heat tube issue described above for the same HP part number. The two slightly different Z440 ones have two "cooling box" attachment screws. One type has two on one side only, but the other type has two screws with one front and one back. I've thought that second type is a bit better for attaching the big cooling block to the base plate. The base plate itself is also shaped a bit differently but both types use the longer processor socket screws, and I've never had a cooling issue with either type using the stock screws that come with them. My thermal paste amount is just a bit thicker than you can see through... spread pretty thin.

[Snoopmasta]

Hey and good morning.

Thank you for the reply. I read nearly all of your posts already before I even started buying the parts. This is also the cause of me creating that account to share some stuff.

Concerning the PWM braking...yeah I read that as well and have been curious. After thorough load testing my system I have to wonder. My fans seem to ramp up as intended. 

Maybe I don't grasp the idea behind how this could affect me. But right now I'm happy with the Noctuas. I even replaced the fan in the PSU (just re-pinned the original plug)

Everything is working fine.

Edit: For the mounting cages of the original fans - I removed all those little plastic noses that poked out (coding) to fit into the fan shrouds of the originals. That's why I have standard width Noctuas all around. I've seen a post with a thin one as exhaust fan. Since those "noses" have no purpose with the original fans when it comes to mounting I removed them and made the Noctuas fit "as is".

Greetings

[SDH]

Sorry for the delay... I had to go dig into my stash of spare parts to put the pics below together. I want to first address the issue of possible slack space under the double-cooling-capacity Z440 heatsink/fan if used on a Z420/Z620 motherboard. That is not the case at all. There is no need to use other mounting screws with that combination. Here's the proof:

I got out a spare Z420 motherboard and processor, put them on without thermal paste, got that big heatsink/fan, put that on the processor socket with a 1.5" wide strip of paper (instead of thermal paste) between them, screwed them down as I always do (to gentle snug after the screws bottom out) using proper technique. The paper was stuck tight in place. Did the same thing with a spare Z640 motherboard and processor and did the same thing... the paper was stuck just as tight with that combination too. The paper thickness is equal to my thermal paste use. I could pick up both motherboards by the paper with no slippage at all. Pics:

Z420 with Z440 heatsink

Z420 motherboard and Z440 heatsink above.

Z440 processor with Z440 heatsink

Z640 motherboard with Z440 heatsink above.

I hope this helps you and others with feeling confident that you don't need to alter the screws from what comes with these excellent heatsinks. If you're using a HP active-cooling memory "saddle" those fit over the top of these heatsinks with about a credit card's thickness to spare.

Regarding Noctua PWM fans... I like them a lot. Their bearings can't be beat, and they run quiet and slow. Seem to last forever. Here's the issue:

The HP workstation's fan/cooling control system does not measure RPMs for each fan and then adjust each to reach a specific fan speed via altering the PWM control signals. Instead, it relies on prior engineering testing by HP (with the case cover on) using different test fans to reach necessary airflow in different areas of the case.  Thereafter, depending on the user's adjustment of overall fan speed needs via BIOS, PWM braking is applied to a greater or lesser degree. Same idea for if temps start to go too high. If you search for the OEM datasheets on the individual fans that HP uses those usually rated to run at high or very high speeds when no PWM braking is applied. Voltage is kept at a constant12VDC. This gives the workstation a lot of headroom for boosting fan speeds when the user chooses that (or the motherboard demands that for self-protection).

So, when the standard HP PWM fan/cooling algorithm is applied to a non-HP-selected slow running PWM fan such as a Noctua it will slow that fan down even more to potentially too slow. Using Noctua PWM fans with your hot fast memory and processor could allow too much heat to build up, depending on what you're doing with the workstation. If you're not pushing it hard then it won't be an issue, generally. You're skilled and I'm sure you've been monitoring that. Others won't always know this stuff or be careful enough. So, in general, my advice on fans is to use what HP provided, especially if you're going to push a workstation hard with video rendering or gaming.

[Snoopmasta]

OH WOW - such an effort!

Cooler: The thing is - the system is running fine now and I had to change those screws. With the others there has been zero contact. The applied thermal paste didn't even leave a mark on the cooler - with all 4 screws fully seated.

I believe you, when you say that you never had this and honestly - I would doubt my words as well if I hadn't seen and done it myself. Maybe I do have a strange combination of unicorn hardware here or I made a mistake - both possible.

If I had the patience to take it off again and repaste the cpu, change the screws again ... I would gladly. Lets agree to do this another time. I'll try to get this done one day and I'll definitely post it here! Promise!

PWM:

Ahhhhhh, now I get how the system works! Thank you for that explanation!

The system runs fine under heavy load and all the fans ramp up the way they should.

Also nice to see that the "liquid cooling" CPU0 LC fan is reporting its RPM as intended.

minimum fan speed in idle

roughly maximum fan speed under constant load

What I don't get though is that the Noctua low noise adapters have no effect on the rear case fan. On the memory fan it limits the max RPM. On the rear case fan the controller seems to raise the voltage as much as it needs to get to its target RPM. There is no way to get it down from its 1400 RPM in Idle or the 2000 RPM under load. Even 2 adapters change nothing on the 1400 idle RPM.

I'm a little disapointed by that since the rear case fan is the loudest thing in the whole build.

This seems to be intentional by the HP engineers but it's annoying.