Pillar CU unable to boot

Upon replacing a slammer CU MB , boot process loop , showing below errors :

I2CByteBangRead: slave failed to ACK byte transfer

HE PS rd byte failed. addr=b2 reg=b

Also clamp seems to be disabled :

==========================

DBG:  ClampStatus    00

ClampStatus_disabled

MEMRESET clamp is currently disabled

clamp_status  0x00

Brd4 BoardInit4 NmiArmed MemClamp_disabled BbmMaintSlfRfrsh Speed Par PciEnum

*** BootType=02 ***

PO reason bits = 0400,

PO_BOOT AgesaPodr=0

when re-running mccAgent , clamp is being enabled , all boot msgs looks normal , but boot msgs simply stops with HW DOG exiting msg

MCCAGENT- 02/07/2017-09:58:33 fofb_check_active() AM_ACTIVE (4, 4) active_candidate=-1

Time out: HW Dog process is exiting