installing 2nd CPU module in HP Z640

[arikkat]

I purchased an a HP second CPU module in order to use a upgrade my Z640 to a dual-CPU system. I already have matching processors. When I went to install the module it was apparent it would not fit in the case. I lined up the connectors on the motherboard and the module and it looks like the heatsink installed on CPU0 is blocking the module insertion - it's way too big. The HP part number for the CPU0 heatsink is HP 749554-001. The part number for the corresponding much smaller heatsink on the CPU in the module is 749597-001. What is the HP part number of the heatsink/fan that needs to be installed on CPU0 in order for the the 2nd CPU module to fit? Is it the same as the one installed on the module? TIA -AAU

[SDH · Accepted solution]

You are right.... there are 3 total heatsink/fans for the Z640 and the big one you have is my favorite, which I can convert easily over for Z620 use (assuming no second processor riser is present).  It just takes swapping the original fan from the Z620 heatsink over to this Z640 heatsink (the Z620 fan plug end has 5 holes, and this Z640 fan's plug end has 6).  It turns out all the Xeon processors for the Z640 and above have different base pinouts so the sockets are not compatible on a pin-morphology level, but mechanically the heatsink base-to-socket morphology between the Z620 and the Z640 are the same.  So, you cannot put a Z640 processor into a Z620 socket and have it work, but you can mount a Z640 heatsink/fan over a Z620 processor/socket and it fits just fine.  That is how I get about 2x the cooling fin surface area over my Z620 souped up processors... use of the 749554-001 with a few fan/fan plug mods.  Enough of that....

All the fans for the heatsinks listed below have just 4 wires coming from/to the fan rotor but the plug end gets creative.  Here's my decoder ring:

Riser heatsink/fan is rotated on processor axis by about 45 degrees, with a 4-pin fan plug to the riser PCB... see 2nd pic below (assembly P/N 749597-001).  This should have come with your 2nd processor riser kit.

Mainboard heatsink/fan (if riser installed) is a straight form factor, with a 6-pin fan plug to the motherboard (AS P/N 749596-001).  This is the part you are missing.

Mainboard heatsink/fan if no riser is installed is almost 2x surface area of cooling fins larger, with same type fan and also 6-pin fan plug to the same motherboard 6-pin header (AS P/N 749554-001).  This is the large mainboard heatsink/fan you have but that won't fit when the riser kit is installed.

So, here is what you specifically need... search eBay for 749596-001.  Note the 4 heat tubes present.  The similar looking heatsink/fan for the ZX20 workstations only has 3 heat tubes and it can easily handle 140W max TDP:

Below is the riser for the Z640 and note that its heatsink/fan is built rotated about 45 degrees so it can fit over the processor and still have the fan blowing straight back. 

Use the 3 part numbers above to see all three in detail via eBay.  Sort by lowest cost first..... the range of prices is significant.  The one you need was $250.00 in one offering and in another offering it was $39.00, both used.

[arikkat]

Hi,

Based on your reply, I purchased a new HP heatsink/fan 749596-001 and today successfully installed it along with the 2nd CPU module. My Z640 that I'm using right now is now a dual-CPU workstation. Thanks!

[SDH]

Happy to help.... you meant you bought 749596-001.... we want others to know the correct number!

[arikkat]

Yes 749596-001... I corrected my post.