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HP Recommended
HP Z400
Microsoft Windows 10 (64-bit)

Hi i m new here, raised with just an unknown issue with my z400 (6 dimms version).

My PC specs 

Processor : w3550

Ram : 4gb (2x2gb ECC unbuffered DIMMs)

Hard disk : 250gb Seagate

Windows 10 Pro 64-bit


This is what exactly happened, i have 2 sticks of ram installed in DIMM 1 and 3 (Black slots).

And installed a gpu amd hd 5450 on pcie x16 slot, i have 5 beeps issue with red light flashing 

I checked my both ram sticks in other z400 it work fine.

I remove gpu then check, its again 5 beeps , then i go for only 1 ram stick in DIMM 1 ,no changed happens, i i reseat rams rn different slots but non of these make any change, then i going to reset the bios by disconnect all wires and drains power of the mobo remove CMOS battery for 5 minutes and press and hold the CMOS button for 30 sec to 1 minute , but none of these work, i reseat my gpu with other pci slots but the beeps keep indicating memory issue, please help me

One thing i noticed , when i put the ram in black dimms slot (1,3,5) and press the power button the 5 beeps begin to early and when i put in white slots (2,4,6) then press power button the beeps came late.


I want to help to fix it please help me, this is my first post, 


HP Recommended

1,3,5 is the correct load order are you sure the ram is unbuffered ECC? please list ram part numbers


have you tried each memory module by itself in slot one?







HP Recommended

Yes, obviously the ram is unbuffered and ecc compatible memory :

Here is the ram part number : 

Hynix HMT325U7BFR8A-H9 PC3L-10600E 2GB ECC 1RX8

I have 2 sticks of same brand and configuration, and as i said i already checked both of sticks in different machine and they work fine, i also check in order, check every dimm slot vise versa, but none of these work


I really curious, why it happening,

One thing i deeply noticed when, every electronic device passed current it become little warm and consume heat, according to this phenomenon, i place both sticks , each in dimm 1 and check the heat during post after 5 minutes i check it still cold, means no current pass i also check remaining dimms by following order but same result. 

HP Recommended

your listed ram is indeed the correct part, and if it tested good in another system you are left with only several things to check


1. cpu, modern cpu's have the memory controller onboard a bad cpu may be the cause


2. cpu socket pins bent, or cpu pads covered with grime (check both and if possible replace cpu)


3. power supply issues run the z400 "BST" test by removing all pwr supply connections to motherboard except for main power cord and turn on supply did light at rear glow green (OK) or red(BAD)  see z400 service manual for bst details


4.bad pci-e card installed, remove all cards, and attached drives does beep code change? (try new video card)


4. defective motherboard

HP Recommended

I  removed the heat sink and uncap the processor, there is no bent pin i also fresh the processor contacts by cotton and alcohol, and recap se cpu again with fresh thermal paste again the same 5 beeps then i pulled his power supply and install the other one (pulled from working z400) but again no luck same result, since there is no pci or pci e card installed so its preety much a defective motherboard i guess, but i m sure its not ram slots issue, something may be wrong with ram or cpu capacitors but is i look there is no physical damage, i think replace the mobo its only an option left.


If you have more troubleshooting left kindly share with me.

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