Z620 Dual CPU, Sudden Display failure

[gerulag]

Intermittent sudden loss of pisplay followed by reboot! More frequent occurrence!

Recent onset of failure to display accompanied by rapid onset of loud excessive fan speed during cold boot! Remedied by reseating CPU1 assembly! Unfortunately recurred after several successful cold reboots! Many recurrences which responded to reseating CPU1 assembly!

Finally reseating CPU1 assembly did not work! Removal of CPU1 assembly allowed the normal POST and operation of Z620! Of course with the loss of the use of full memory and 2nd CPU!

With only CPU0 Onboard Diagnostics showed RAM OK, C:\ Drive OK!

Any suggestions appreciated! Possibly remove and reapply CPU1, test CPU1 RAM, etc. 

[MtothaJ]

---

@gerulag wrote:

Intermittent sudden loss of pisplay followed by reboot! More frequent occurrence!

Recent onset of failure to display accompanied by rapid onset of loud excessive fan speed during cold boot! Remedied by reseating CPU1 assembly! Unfortunately recurred after several successful cold reboots! Many recurrences which responded to reseating CPU1 assembly!

Finally reseating CPU1 assembly did not work! Removal of CPU1 assembly allowed the normal POST and operation of Z620! Of course with the loss of the use of full memory and 2nd CPU!

With only CPU0 Onboard Diagnostics showed RAM OK, C:\ Drive OK!

Any suggestions appreciated! Possibly remove and reapply CPU1, test CPU1 RAM, etc. 

---

Have you tried monitoring your temperatures when the machine is running? It may be a CPU cooling problem, with thermal protection kicking in and triggering the loss of display / reboot.

[gerulag · Accepted solution]

Hello MtothjaJ,

I went into the cmos and increased fan idle speed to maximum, but when the CPU1 unit was installed, same problem, computer on, display on, no video display, fan speed maximum but no display!

So I swallowed my pride and reseated the CPU1 RAM, uninstalled the CPU1  and reinstalled it after cleaning and reapplying heat conduction paste! Result, no change, computer on, display on, no video signal, high speed fans!

Uninstalled CPU1 assembly! Went into CMOS and restored fans to minimum idle speed! Reboot, normal POST and access to Windows 7 PRO 64 bit!

Brain now discouraged but not defeated! Very close inspection of CPU1 assembly! Suspicious tilt of connector located to the Right Edge of assembly protected by a metal guard! I cautiously centred the connector within the guard and placed the CPU1 assembly back in place!

Now the Z620 is assembled with both CPU0 and CPU1, cold boot, presto, POST normal, display normal, access to Win 7 PRO 64 bit restored! I then exited and shut down! Second boot, all is well, POST normal, diplay normal, accessed the internet and answered the email!

Thank you for your assistance, and I am relieved that this Z620 is functioning properly again!