New machine powers up for a couple of seconds by itself every now and then, fans spin, lights on, then it turns off again. Some of the intervals seem regular and at other times it does it a couple of times within 20 seconds or so, otherwise about once every 20 minutes. Apart from this it works fine. Wake on lan is not activated. Thanks.
and check your ram or even better buy new ram i had the same problem had a gig and 512 mb, pc restarted by itself then i removed the 512mb and its perfect
All power options are disabled in bios. Updated bios, reset to factory. Ram seems fine, I've tried all combo's and it's still happening. Weird one, I've had similar things happen with dodgy kettle leads and extension plugs but I've ruled all that out his time, no idea.
The problem is not with random reboots...the problem is that the system turns itself on, then back off. I have to say this is a weird glitch...especially without power management, or WOL, and with the power and reset switches ruled out (I assume the system does the same thing with them unplugged). The issue almost has to be either the mainboard, the PSU, or the settings in bios. I know you have turned of power management and WOL, but sometimes bios options are glitched so that "off" is really on, and vice-versa. Other than that, the only way I can think of this happening is if there was a intermittent short of some kind in the mainboard or PSU...more likely in the PSU.
I had an old Compaq machine do this, very spooky. The machine eventually got sent to the great motherboard grave in the sky, there was obviously a motherboard problem of some sort causing the machine to randomly switch on and enter our mortal coil. I had swapped out the PSU and it still did it hence why i blamed the motherboard
Since last posting I changed the ram (inital config was 512mb x2 and 1GB x1) to a single stick of 2GB. I updated the bios to the newest version, I've gone back to the version before that, took the system battery and power lead out for a while, disconnected the main power from psu to mainboard, tried it with 3 different cr2032 batteries (one brand new), the bloody thing is still happening... I suppose next week I'll have to go through trying it with another psu and mainboard.
I've swapped that box for a whole new box, it's still happening on this one as well! I've tried 3 different bios' in case the bios settings had been programmed wrong. I'm thinking now it's some kind of feature, don't know, will probably phone Dell at some point but since it's out of warranty don't know how much they'll tell me. The user will have to live with it for now, minor problem anyway.
check the power on button and the power on wire could just be a short that turns it on and then of course turns it off, interesting problem also check a loose screw isn't wedged agianst the on / off pins
No, what I mean is, I've swapped the whole machine for another different optiplex 755 and it's happening on the new one as well, that's why I suspect it's some sort of feature or something similar.
It's happened in 2 different locations so pretty sure it's nothing to do with the plugs. There's no power key on the keyboard. I did find this lead though which I'll be checking later: http://en.community.dell.com/support-forums/desktop/f/3514/t/19005062.aspx?PageIndex=2
That fixed it, went into the mbex bios by pressing ctrl+p and disabled it and it stopped! Wish I had googled this more thoroughly before carting the thing around and swapping it for another. Must remember for future that there are sometimes more than one bios.
