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Asset ID: 1-73-1000316.1
Update Date:2010-08-30
Keywords:

Solution Type  FAB (standard) Sure

Solution  1000316.1 :   When remounting heatsinks during CPU replacement on K2.5 and S2 CPU Aux boards - the old style spring-nut for the heatsink attachment has a tendency of breaking the standoff-screw.  


Related Items
  • Sun Fire V20z Server
  •  
  • Sun Fire V40z Server
  •  
Related Categories
  • GCS>Sun Microsystems>Sun FAB>Standard>Reactive
  •  

PreviouslyPublishedAs
200434


Product
Sun Fire V20z Server
Sun Fire V40z Server

Xoption
  • Xoption Number: X7243A
  • Xoption Description: Two (2) AMD Opteron 848 CPUs (2.2 Ghz), (w/VRMs, Heatsinks, Daughterboard)
Xoption
  • Xoption Number: X9862A
  • Xoption Description: Two (2) AMD Opteron 850 CPUs (2.4 Ghz), (w/VRMs, Heatsinks, Daughterboard)
Xoption
  • Xoption Number: X9863A
  • Xoption Description: Two (2) AMD Opteron 852 CPUs (2.6 Ghz), (w/VRMs, Heatsinks, Daughterboard)
Xoption
  • Xoption Number: X7245A
  • Xoption Description: Two (2) AMD Opteron 854 CPUs (2.8 Ghz), (w/VRMs, Heatsinks, Daughterboard)
Xoption
  • Xoption Number: X9895A
  • Xoption Description: Two (2) AMD Opteron DC 870 CPUs E Stepping (2.0 Ghz), (w/VRMs, HS, CPU 2nd board)
Xoption
  • Xoption Number: X7249A
  • Xoption Description: Two (2) AMD Opteron DC 880 CPUs E Stepping (2.4 Ghz), (w/VRMs, HS, CPU 2nd board)
Xoption
  • Xoption Number: X9896A
  • Xoption Description: Two (2) AMD Opteron DC 875 CPUs E Stepping (2.2 Ghz), (w/VRMs, HS, CPU 2nd board)

Impact

If the standoff-screw is broken, the heatsink might not make proper contact with the CPU, which is needed to draw the heat away as necessary. The end result could be over-heating and the system could shutdown.


Symptoms

This issue is seen when the heat sink is replaced on the Khrepri line of products as well as the Sobek Aux CPU assemblies. These heat sinks are attached in their original form with spring-nuts. The base standoff-screw was installed on the mother card. This standoff has a screw machined onto the top of the standoff (standoff-screw). When mounting the heatsink, the heatsink mounting hole is placed over and around this standoff-screw. There is a fairly large gap between the screw shaft and the inner wall of the heatsink hole. This gap creates a situation where the heatsink can be tilted and not level or parallel with the mother card. When the spring-nut is inserted into the heatsink hole, it aligns with the tilted heatsink. When the spring-screw is tightened, it cross-threads itself and binds. Tightening the heatsink to the proper position is met with the screw breaking. This could result in an over-heating situation.


Root Cause

When the heatsink is installed in a non-parallel position to the motherboard, the spring-nut could be cross-threaded on to the standoff-screw.  When this occurs, the spring-nut might bind on the standoff-screw and break.


Workaround

Replace spring-nut with a Heatsink Spring Screw attachment. When this is done, the standoff-nut will align the heatsink to the motherboard and the spring screw will be correctly aligned for proper attachment.


Resolution

*Instruction on changing the old Khrepri SFRUs and Sobek Aux CPU FRUs.*

1. Unbox and open chassis or Aux CPU card.

2. Carefully remove heatsink by loosing each of the spring-nuts evenly.

3. Remove all four standoff-screws/spring-nuts and scrap but keep the flat washers.

The following are precautionary instructions after heatsink, spring-nuts, nut/standoffs are removed:

  1. Replace the standoff-nuts on the card.
  2. Tighten replacement standoff-nut by hand.
  3. Without creating contaminates, with a properly sized (13mm or 1/2 inch) wrench tighten the standoff-nuts a quarter of a turn.
  4. Seat the heatsinks down on the processors after thermal grease is applied.
  5. Install flat washers that came with the old assembly.
  6. Install the new spring-screw by making sure not to cross-thread by hand.
  7. With a phillips screw driver tighten evenly, each spring-screw till they bottoms out.
  8. This ends the procedure.

Additional Comments:

The attachment for each heatsink must be done evenly. This means that each spring-screw must be tightened by turning them equally. This means that the first spring-screw must not be tightened all the way followed by the last spring-screw.

Special Considerations:

Application of thermal grease must be done by following set procedures. Warning: Excessive use of thermal grease will damage the CPU socket and and could cause system malfunctions.


Previously Published As
101999
Internal Comments


This is used on the Sun Fire V20z System Board and on the Sun Fire V40z CPU/Memory Daughter Board.  




  • The new part is installed in V20z Super FRU 380-1194-03.  


  • The new part is installed on V40z CPU/Memory Daughter Board 370-7778-02.



The dash level of the chassis FRU is not indicated on the part number label inside the chassis. A chassis shipped as a system do not include the FRU part number on the outside of the chassis.  A chassis shipped as a new FRU does include the FRU part number on the outside of the chassis. External labeling of a chassis that originally shipped as a system and has been repaired and returned to service inventory is unknown.  



How to locate the affected part:





  • Release Notes 819-1771-17 includes an illustration of the new design.





  • No illustration is available of the original design.







  • The part does not have a part number label.





Old style spring nut information:





  • The old part did not have a sun part number.





  • The old part was installed in V20z Super FRU 380-1194-02.





  • The old part was installed on V40z CPU/memory Daughter Board 370-7778-01.





  • The problem does not affect V20z Super FRUs 380-0979 or 380-1168





  • The problem does not affect V40z CPU/Memory Daughter Board 370-6927





New style Heatsink Spring Screw kit information:





  • The new "Heatsink Spring Screw" kit part number is: 371-0849





  • quantity of parts per kit is unknown





  • two screws per processor are required





  • the system board can have one or two processors





  • the cpu/memory daughter board always has two processor





Hardware Remediation Details

 


Related Information
  • ECO: WO_31526
  • Other: Newisys Support Center ticket 3850

Internal Contributor/submitter
[email protected]

Internal Eng Business Unit Group
KE Authors

Internal Eng Responsible Engineer
[email protected]

Internal Services Knowledge Engineer
[email protected]

Internal Kasp FAB Legacy ID
101999

Internal Sun Alert & FAB Admin Info
Critical Category:
Significant Change Date:
Avoidance: Service Procedure
Responsible Manager: null
Original Admin Info: null

Internal SA-FAB Eng Submission
When remounting heatsinks during CPU replacement on K2.5 and S2 CPU Aux boards - the old style spring-nut for the heatsink attachment has a tendency of breaking the standoff-screw.

Product_uuid
1acc55b3-4b82-11d8-99fc-080020a9ed93|Sun Fire V20z Server
4726b78d-56d2-11d8-9e3a-080020a9ed93|Sun Fire V40z Server

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