Hi @Dr-Frankendell,

Thank you for marking my answer as a solution and the feedback.  I'm glad you got it working again.

I recently had to re-seat my RAM per the error code.  When the error code came back later, luckily, a restart took care of it.  I realized my RAM is a little dicey and is probably showing its age.  It doesn't like too many things open on the taskbar and it doesn't come back from standby/sleep.  Depending on how much activity, probably my safest bet is to restart to clear out the RAM before putting back to sleep. - Until if I get new RAM.

I bet your T5500 still whips.:Smile:  Still a smart move getting a newer computer and having the T5500 as a backup.

Thanks for your attention to my problem.  In the end, I removed the wifi adapter card, GPU, and all hard disks with no change in behavior.  Then I re-seated one of the DIMMs and ... everything suddenly went back to normal (and remained normal even after I reconnected everything else).  In the meantime we procured another computer to serve the role of this one, so I now have a sandbox system on which to mess around with server-ish stuff. 

bradthetechnut:

I have an interesting problem, maybe you can give me some suggestion, I just got an old T5500, I installed Win10, everything works great. But when I do a hot restart, then the system will power on a few seconds and off, and keep forever.  The system cold starts fine and can work for hours no problem. just wonder what can cause this start failure when the system is hot. 

thanks,

David Sun

I do have a couple of suggestions.

Replace the CMOS size 2032 battery.  A low battery can cause all sorts of bizarre problems.  Duracell lithium or Energizer lithium is suggested.  They should last around 5 years.  Yet I only got 2 years out of Sony.

Is the inside clean - including the fans, heatsink, and etc.?  I'd also replace the thermal paste.  As long as you bought it used, it's hard knowing the last time it was replaced.

And of course, please let me know how it goes.

bradthetechnut

P.S.  I'm not sure what you meant by "keep forever."  It shuts off and won't turn on "forever"?

it will on few seconds then off a few seconds, and loop forever. it kind of related to thermo. because I unplug the power cord for a long time, then it can power on without a problem and can keep working for a long time. if you power off and turn on again, then the on and off dead loop happen. 

the problem is not fatal, but it is there. 

have a great weekend

If you want, download HWiNFO64.sys.  You can also keep an eye on temps and verify it's not a temperature issue.

The 3v battery might also seem unrelated, but you might be surprised.  It's often the first thing to check.  One can also test it with a battery tester if they have one handy.

Due to the T5500's age and buying it used and not refurb, I still stand by my suggestions posted above.  It's definitely where to start troubleshooting.  Is the PSU clean?

You have a great weekend also.

P.S.  It's been hit or miss if I receive an email when somebody replies, so sometimes my responses are a bit delayed.

Another suggestion, as pasted from another post:  We suggest you run the hardware diagnostics to check is there any hardware faults. To run diagnostics, restart the computer, as the computer boots, press < F12 > when the Dell Splash Screen appears. When the Boot menu appears, highlight the Diagnostics option and then press < Enter > to start the Diagnostics. If you get any error code and validation code, capture and lets us know.

status update of the troubleshoot, 

it passed the F12 diagnosis test without any problem. I let the memory ran for 30 minutes, then stopped it.

https://drive.google.com/file/d/1QGEEqdCDm6Tf4L5o99DGpcEOKLmC7iLR/view?usp=sharing

after I click Ok. the windows 10 not boot. because the system runs the diagnosis program for 30 minutes.

the video clip at this link shows what the computer trying to do something. 

https://drive.google.com/file/d/1qBizJWhatAeinrCidlnYkBWEviYKisuS/view?usp=sharing

if I unplug the PC for one day, and start from a cold state. it can boot to win10 and run without any problem. 

It may be related to the power supply, but I don't have a good one to replace. I will try to check the thermal paste solution later. 

I appreciate your suggestion and help. 

https://www.dell.com/community/Precision-Fixed-Workstations/Precision-T7500-BIOS-reboot-problem-is-preserved-in-new-A17/td-p/6135817

I guess this is the problem because I did update the bios to A18. if what claimed in this post is correct, 
"The only solution was to downgrade the BIOS to the A09 version, which I did so. And that is the solution you will find on the web for this problem"

I don't want to downgrade to A09. I guess Dell didn't make a perfect solution. I can survive always power off the system and wait hours later to power it on instead of to do a restart. I wonder if it worth to update a solid disk for it.