T1600 CPU fan failure / Pin layout

Hi,

the CPU fan in my T1600 has failed and I ordered another type of CPU fan with 4 pins (Alpenföhn Ben Nevis).

Unfortunately, the plug of the new fan does not fit into the socket on the T1600 mainboard (4pin instead of 5pin and thicker than the old one), so I have to build an adapter with the old fan cable. Unfortunately, I only found a pinout for the Optiplex 755 here in the community and don't know if the pinout is identical on the T1600.

Can you tell me what the pin layout of the old T1600 fan has to be? Thanks in advance!

Addendum: There is a XEON E3-1270 CPU on the mainboard.