i have a dell optiplex 755 (tower).. it was working fine.. but one day when switched it on,, it doesnt behave normal.. and no screen was showing on the monitor.. the pc was showing the orange light instead of green.. i switched it off and again turn it on after few minutes.. it was started normally and was working absolutely fine.. after some days same prob was happen.. i repeat the solution and it was working.. one day i switch on the pc it shows the dell logo then goes at a black screen showing a blinking cursor.. i was stuck there for hours and pc was like hang.. no key was working at keyboard.. as i want to go to setup but after pressing f2 it doesnt take me in setup and the black screen keep showing a blinking cursor.. in this state the lights which are on the front panel,,were green.. but not all.. 1st 2nd and 3rd lights are on (not blinking) continously on.. it happens when pc hang just after the dell logo comes on switching it on.. i as so fed up with this so i decided to open the casing of my pc.. i was thinking that RAM or Hard drive can be faulty.. i plugged out ram.. it was looking fine.. just plugged it in the same slot from which i plugged it out.. the prob repeated.. then i plugged out the ram and then plugged it in 4th slot which is wrong one.. (because the ram should be in the slot near to the processor, which is slot 1) after putting it in slot 4 pc starts and after dell logo it shows the message about ram.. dont remember it.. it was something like populate dimm 1.. just after this message it was showing to boot press some key (which i dont remeber ) and for setup press F2.. i pressed f2.. i took me to the setup..i checked out there.. my hard disk was detected.. and the ram was also there in slot4.. i thought now every thing will be fine.. i just restart it after dell logo it showed the same message to populate dimm1 (which was because of wrong selection of the slot for ram )then it show to boot press some key ( which i dont remeber) i pressed that key i took me to the windows 7 logo but.. at that time when the four window logo of window7 was showing animation the pc hangs and restart.. this happend sveral of times when i repeat the procedure.. finally i plugged out ram and put the ram in Slot1.. the same prob happened the black screen with a blinking cursor.. in the sate of pc hang.. and was unable to go in setup..showing 1st..2nd and 3rd lights green (continously on not blinking).. after some days i plugged out 2 ram sticks of 2gb each from my brothers pc which is dell optiplex 745 (desktop) and then put his ram sticks in my pc in slot 1 and 3..the same prob occurred.. after dell logo there was black screen showing a blink cursor..and 1st , 2nd and 3rd lights were on in the state of pc hang jus after dell logo.. i just want to add the behavior of my keyboard.. when the pc hangs after the dell logo the numpad light of keyboard was also switched on and after pressing num lock key it was not turning off.. the keyboard was also stuck with the system..the keyboard is working fine at my brother`s pc.. iam so fed up with this... please help me
Here are the diagnostic lights <ADMIN NOTE: Broken link has been removed from this post by Dell>. Green 1, 2 and 3 with 4 off means "other failure". It is recommended you check the drive connections.
Please do not just start pulling random components out. That is not the way to diagnose a problem with your computer.
You may have a problem with your hard drive, so you should try to boot to your drivers and utilities disc to run the diagnostics.
Please post back and let me know if you need more help.
i have already done these things.. check all the connectors with hard drive.. i dont think so that its the case of hard drive failure.. because if that so, it will not take me in to the setup only by pulling ram out of Dimm slot 1 and putting in slot4..
Another thing is that i have tried to boot from the cd.. it is not going to boot from the cd.. and stuck on the black screen.. i hit F12 to go to the diagnostic tests.. when i hit F12 it took me to the screen where it was asking for the diagnostic test..i select the diagnoistic tool.. but nothing happened and the pc stuck there... the highlightened cursor also hanged and not moving up and down after selecting any of the option..
waiting for ur help n for ur help thanx..
I am having a similiar issue. The computer hangs during boot up. The splash screen comes on and the diagnostics lights are 123 then 1234 then 12 then 23 then 123 then it hangs at 123 and never finishes. If I hit F12 during the splash screen the one time boot menu comes up, but after I make any selection and hit enter, it hangs there. I've been having this issue for awhile. Two weeks ago I contacted Dell about the problem and they sent me a new motherboard. After installing the motherboard everything worked fine, now the computer is doing the same thing again. It is a Dell Optiplex 980. I have checked all the drive connections and they seem connected fine. I have not tried a different cable for the harddrive or the DVD drive.
yes my prob is just like yours..it means its not the problem in the motherboard.. iam fed up with this prob.. plz some one help.
Can you enter the BIOS (F2)? If so, go to boot devices and set the first boot device to be your CD drive. Then try booting to your drivers and utilities disc.
If that doesn't work, then go to Dell downloads for your system and download the diagnostics utility. Obviously, you'll need to use another computer to do this. The installation instructions should include a method to prepare a bootable flash drive with the diagnostics on it. Use that to boot your system to run the diagnostics.
sir, i was not able to go in to the BIOS.. as it tooks me to the black screen just after dell logo.. i hit F2 at the dell logo screen but nothing happened.. and it took me to the black screen with a blinking cursor... BUT, when i plugged out my ram from SLOT 1 and put it in Slot4 alone.. the pc boots and showed an error message to po populate dimm1 ( i know it is because the slot 1 is empty) but when it was showing an error message to populate dimm1.. there was also 2 options there to go to the setup or boot from hard disk.. i select go to the bios setup.. i went to the setup.. all things were looking ok there.. i change the settings of boot sequence to boot from Cd/DVD drive first.. then i restart my pc and put a win 7 bootable dvd in my dvd rom.. it showed me the same error message to populate dimm 1.. i ignored it and this time i select boot.. then it showed me the win 7 setup screen.. i was going to install a fresh copy of win7.. but after 1 minute the pc restart automatically... the same procedure repeated many times.. but this all was happened when i put my RAM in slot 4 alone... ( which is a wrong one) i have to put it in slot 1.. but nothing is going to work.. no booting.. not going to bios with ram in slot 1 alone.. please reply for help.. thnxx
I found an answer online that worked for me. I have a 1 TB external USB drive that I keep plugged in. I unplugged this drive and the computer booted right up. I can't say for sure this was the fix, but it worked today.
yes i also keep plugged in my usb (8GB).. but i plugged it out when the prob starts.. but nothing is working..
should i try to plugged in that usb ?? and try to boot ??
also i have a network cable always connected to the pc.. but now i unplugged all the things... usb and network cable.. ( i thought many times that my computer is searching for the network boot or the boot from usb ) but iam confused what to do
You may have bad ram. 1 2 3 on not blinking means the system is sitting at F2 setup screen and waiting for user input.
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sir i have mentioned in my post that i have used working pair of ram 2 gb each which is working perfectly fine at my brother`s computer (which is dell 745) and my pc is dell 755.. but the computer behaves the same as it was behaving with my own Ram.. so i buy a new pair of ram it will not work.. if my brither`s ram is not working on it
just a update.. i just on my pc.. insert my own ram of 1 gb single stick...at slot 4.. and the message appears ( populate dimm1) and two options was there to go bios or boot i selected boot from cd.. and entered win7 bootable dvd. now its on setup and installing windows.. i wonder how is it working now.. but it is happening when i put the ram at slot4 which is wrong wrong i know.. plzz suggest me what should i do now