HERE is the forum section for Optiplex support.
On the consumer Desktops with Intel CPU's, there is an Intel (motherboard) Chipset Driver. The chipset drivers MUST be installed before installing device drivers such as the sound. I notice there is a chipset driver for the 745 and if you did not install the chipset drivers that could be the problem.
On consumer desktops with Intel the correct install sequence is (1) Install Windows (2) Install chipset drivers (3) Install device drivers (such as sound). HERE is the downloads for XP and the 745.
I am not a Dell Employee
Dell forum member since 2002
Inspiron 15 - 5577 Laptop
Home Built Desktop PC with ASUS Z170, i7 6700K CPU, Windows 10 64 bit Pro. SSD drive. Sonar Platinum Recordng Studio Software.
Dell SE2717HR 27" Monitor
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Hi installed all chipset drivers, i also uninstalled them all just now and reinstalled them in the order you said, still nothing coming out of speakers from the line in. Please help if you can