Z220 not booting after installing network card(s), 5 Beeps and red power button blinking)

[Jmm1112]

Hi, i tried to install network cards to testlab desktop which serves as virtual server. I have two quad port NICs(see details below) but neither of them works. As i insert these to the mainboard and attempt to boot, HPZ220 just starts beeping 5 times and fails to boot.  Also powerbutton blinks read. Manual says following:

"Red Power LED blinks five times, once every second, followed by a two-second pause. Fivebeeps.
->Pre-video memory error."

Network cards i've tried are: 

HP NC375T  https://support.hpe.com/hpesc/public/docDisplay?docId=emr_na-c01951393

And

DELL I350-T4 PCIe https://www.dell.com/en-us/shop/intel-ethernet-i350-quad-port-1-gigabit-server-ada...

Both are x4 PCI Express and should be compatible with x4, x8, and x16 PCI slots in Z220? 

I've lates bios installed in Z220.

br, JMM

[Jmm1112]

I've searched for internet for possible solutions but did not yet find anything helpful. One thing i found was that there were hints that some pcie slots would be reserved for certain cards? Why is this so?

http://resources.avid.com/supportfiles/attach/AVID_HP_Z220_Tower_Workstation_Config_guide_Rev_A.pdf

5 beeps hint to a problem with display adapter. Is my Z220 expecting my NICs to be display adapters!?