Badcaps.net Forum
Go Back   Badcaps Forums > General Topics > General Computer & Tech Discussion
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 09-17-2019, 12:39 AM   #1
FShahid
Member
 
Join Date: Nov 2012
City & State: London
My Country: United Kingdom
I'm a: Knowledge Seeker
Posts: 48
Default Dell 755 Power Off Immediately After Power Button Press

I have 3 of these Dell 755 with odd problem. All of them has no apparent components failing yet when I try to power them on the amber color power light comes on for less than a second then powers off.

I have replaced power supply, CPU (I have tried several: Q6600, E5500, E4400), same issue EXCEPT that when I install Pentium 4 CPU (which doesn't belong to this model) it keeps powered on with solid amber light and solid network activity light (one board has fan spinning at medium speed, while other 2 boards with normal idle speed).

Kindly let me know what could be the issue, I have replaced CPU, RAM, PSU with no luck...
FShahid is offline   Reply With Quote
Old 09-17-2019, 07:40 AM   #2
stj
Great Sage 齊天大聖
 
stj's Avatar
 
Join Date: Dec 2009
City & State: Europe
My Country: some shithole run by Israeli agents
I'm a: Professional Tech
Posts: 21,451
Default Re: Dell 755 Power Off Immediately After Power Button Press

p4 may use less power,
if that's the case then it could be the capacitors around the cpu area not being as good as they should be.

i have one here with an E8400 in it, but i cant remember what the board looks like!
stj is offline   Reply With Quote
Old 09-17-2019, 09:03 AM   #3
piernov
Moderator
 
Join Date: Jan 2016
City & State: Valbonne, 06
My Country: France
I'm a: Knowledge Seeker
Posts: 1,643
Default Re: Dell 755 Power Off Immediately After Power Button Press

The Optiplex 755 is not compatible with Pentium 4 CPU so that could explain the different behaviour. P4 typically eats more power than Core 2 btw.
It is also not officially compatible with 45nm CPU, so I'd stick with 65nm ones. Q6600 and E4400 are explicitly on the available configurations so that should be good.

Did you try a CMOS reset? Did you try the motherboard out of the chassis with just CPU inside the socket and PSU connected, shorting power button pins to turn it on? Any difference with or without RAM?

Capacitors can indeed be suspected, but rather the ones around the MCH (northbridge) and RAM, the CPU VCore ones are polymer so they should be ok.

Also I don't know for the 755 specifically, but those machines typically power on for a second with amber light when AC power cord is plugged in then turn off. Depending on the BIOS configuration, they will then turn on again automatically or you have to press the power button.
__________________
OpenBoardview http://openboardview.org | IRC #openboardview@irc.freenode.net
piernov is offline   Reply With Quote
Old 09-23-2019, 07:28 AM   #4
SistMaticZ
Member
 
Join Date: Jul 2019
City & State: Casablanca
My Country: Morocco
Line Voltage: 220 V AC
I'm a: Knowledge Seeker
Posts: 72
Lightbulb Re: Dell 755 Power Off Immediately After Power Button Press

Quote:
Originally Posted by piernov View Post


Also I don't know for the 755 specifically, but those machines typically power on for a second with amber light when AC power cord is plugged in then turn off. Depending on the BIOS configuration, they will then turn on again automatically or you have to press the power button.
Hi . I have exactly this same issue . the power goes on and then off automatically as long as the AC power cord is plugged in . And this gets repeated for ever but with long intervals between each on/off (amber light).

Is this normal or a technical fault ?
SistMaticZ is offline   Reply With Quote
Old 09-23-2019, 01:19 PM   #5
stj
Great Sage 齊天大聖
 
stj's Avatar
 
Join Date: Dec 2009
City & State: Europe
My Country: some shithole run by Israeli agents
I'm a: Professional Tech
Posts: 21,451
Default Re: Dell 755 Power Off Immediately After Power Button Press

it could be a fault, but it could also mean it's in sleep-mode.
you need to go into the bios and check that it's not enabled and "off" actually means off.
stj is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 02:44 PM.
Did you find this forum helpful?