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GA-P55A-UD5 Boot-loop; PCI+PCIE diagnostic led keeps on

jcs

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GA-P55A-UD5 Boot-loop; PCI+PCIE diagnostic led keeps on
« on: September 07, 2018, 07:20:13 pm »
SPECS:
MB GIGABYTE GA-P55A-UD5
CPU Intel I5 750
RAM 1 x KINGSTON KHX1600C8D3T 2GB DDR3 connected on DDR3_1
GPU: Gigabyte GT-710
PSU standard 500w

SITUATION:
Out of the box, not visible shortcuts detected
PSU 24 pins connected, 8 pins connected
Peripherals: Only monitor connected, Not keyboard, mouse, hdds, others
Not overclocked.

POWER CYCLE:

1) On connection to PSU:
S4/S5 red led permanent ON
POWER BUTTON blue led permanent ON

2) After push POWER BUTTON:
CPU and Videocard Fans rotate permanent
S4/S5 red led OFF
POWER BUTTON ble led permanent ON
All PHASE LED permanent ON (2 green, 2 yellow, 2 red)
GD1 permanent ON green led, GD2 permanent ON yellow led
MD1 permanent ON green led, MD2 permanent ON yellow led
2a) CPU LED blue led ON 10 ms then OFF
then DIMM_LED blue led ON 10 ms then OFF
then CPU LED blue led ON 10 ms then OFF
2b) then DIMM_LED blue led ON 3 seconds then OFF
then
PE_LED blue led permanent ON
PE1_LED blue led permanent ON
PCI_LED blue led permanent ON

3) After 15 seconds the system reboots
repeat cycle starting in "2) After push POWER BUTTON"
only one difference:
PE_LED, PE1_LED and PCI_LED blue led permanent ON at the beginning of the cycle

4) After 15 seconds the system reboots
repeat cycle starting in "3) After 15 seconds the system reboots"

The speaker never beeps
The monitor not receiving signal

I TRIED:
Replace PSU (New PSU 750w)
Replace GPU
Replace RAM
Cleaning and recconect CPU
Cleaning all the slots PCIe + PCI
starting without GPU
clearing CMOS (disconnect PSU, push power button about 1min., extracting battery about 1 day).
Always the same issue

I tried to start without RAM then after 2b) repaeating infinite cycle starting in 2a) to 2b)



RESUME:
I suspect a fail on PCIE/PCI bus, maybe on P55 PCIe bus, maybe on TSB43AB23 or IT8213 controllers.

Any suggestions will be wellcome.