Z640 Fans Loud after adding NVMe via a PCIe adapter

[Global33]

I've got an odd problem. I added a NVMe to my HP Z640 using a Sabrent PCIe adapter. After I've done this the rear fans are a lot louder and as it's close to where I work, it's pretty unpleasant.  I've tried it in a PCIe x16 and x8 slot with the same results. Now I have now removed it and my system is back to being being very quiet. I've only got one CPU in this device.

It's not more heat that's causing this, so I'm wondering if there's anything I can do it to stop it?

If not does anyone use an official HP convertor which enables you to boot from the PCIe slot? Downside is that's on a x4 slot which I believe is just Gen 2, but I could live with slower speeds more then I can the noise! 

[Global33]

Well despite the tumbleweed, I'd thought I'd put this here as this post is now on the first page of Google and I don't want it to like that XKCD cartoon.

If you stumble across this, my solution was to  go into BIOS and change the bifurcation settings for the PCIe port that it was plugged into to 4x4x4x4

[SDH · Accepted solution]

Find HP Z440, Z640, and Z840 Workstation Series Maintenance and Service Guide. This is a manual with part number 748721-004 and is the latest. I'll focus on the HP recommended NVMe M.2 stick carrying cards, their Z Turbo Drive series. You won't find some of this in that manual because it relates to later BIOS upgrades.

Go to the Z640 section, page 11 shown in the bottom right corner. Note the 6 PCI related slots section in the motherboard diagram there (12-17). Those equal the slots 1-6 on the motherboard. Note that PCIe slots with Generation 3 bandwidth are slots 2, 4, and 5. Slots 4 and 5 are, respectively, the slots that HP recommends placing their Z Turbo Drive single-M.2 SSD adapter cards in as their first and second choices. Slot 3 is possible but not recommended because it is a PCIe generation 2 slot ("PCIe2 x4"). The same holds true for a Z440.

So, for a single-M.2 ZTD G2 card use slot 4 (which is an 8x electrical lanes slot so 4 will go unused). For a Z Turbo Drive Dual Pro running two M.2 SSDs also use slot 4 but change in BIOS its slot bifurcation settings to x4x4. For a Z Turbo Drive Quad Pro running four M.2 SSDs use slot 5 (which is a 16x electrical lanes slot) and change in BIOS its slot bifurcation (quadrification) settings to x4x4x4x4.

Works for me fine... I like that ZTD Dual Pro card a lot in slot 4 because with bifurcation set to x4x4 I have PCIe Generation 3 bandwidth with NVMe M.2 SSD speeds for both my boot/applications M.2 drive and my second bigger NVMe M.2 documents drive. It is much smaller than the ZTD Quad Pro and both do work well in my Z440 workstation. I don't need 4 M.2 sticks running...

HP released this bifurcation/quadrification capability for the Z440/Z640 in recent BIOS versions... before that it was available only on the big gorilla Z840.

[Global33]

Thank you! Bit late as I solved it, but it's nice to know more details. I'm using it as a very quiet server for homelab type stuff, so it runs ESXi, so I imagine I'll probably want to add more at some point and this will be helpful. 

These things are an amazing bargain for what I'm using it for. 18 cores and it makes the same amount of noise as my gaming PC (hardly any)