Desktop computer Forums (Audio, General Hardware, Video)

Dell 4600 won't boot, get flashing A diagnostic light, B yellow, C and D green

  • I have two Dell 4600 computers.
    First a bit of computer history for context:
    Both have had the power supplies fail.  I first noticed that they wouldn't power on without many attempts after being turned off for awhile, although after being on for awhile they could reboot fine.  This indicated to me that the power supplies were getting marginal and if I heated them a tad with a hair dryer they would start.  Bingo, it worked as a temporary fix to getting these guys rebooted if they were off for awhile.  Once on they were fine.
    However, I still ordered two new power supplies (nice 400 watt units) since I knew the Dell supplies were about to die.  I installed in the first one into the first Dell 4600 with no problem, it's now back online.
    I installed the second one: no boot.  I've checked cables and even switched power supplies.  The unit that didn't boot still doesn't even with a known good power supply installed by someone who is now getting pretty good at it... me!  ;-)
    So, here's the symptoms when powering on:
    - The CPU fan comes on
    - The hard disk makes a little bit of sound as if it is going though the power one calibration, but then it's silent.
    - Neither the disk light nor the DVD-ROM disk light flash or come on like they when working 4600 boots.
    - No video (no BIOS boot messages)
    - No sounds, beeps or anything
    - The A diagnostic light flashes green/yellow at about 1.5 flashes per second
    - The B diagnostic light is yellow
    - The C and D diagnostic lights are green.
    This diagnostic pattern isn't listed in the manual, nor is there any mention of flashing diagnostics lights.  The closest listing is if both A and B are yellow, it's a RAM issue.  So I reseated the RAM but that didn't change anything.
    Oh, and I also tried disconnecting the disks and plugged in a different graphics card.  These caused no change in behavior.
    Any suggestions?   I'm suspecting something wrong with the CPU or motherboard.
    Also, what would a replacement (2.4 Ghz) P4 CPU and/or motherboard run me?
  • If you have 2 4600's, can't you try the processor from the bad machine in the good one to eliminate that possibilty?

    I just looked into a new mobo for my 4600 and Dell said it was $140 and out of stock.  From what I heard Dell has made about 3 different MBs for the 4600, so the price might vary.

    I decided that before I buy a mobo from dell, I would buy a new case/psu and something like a ASUS mobo and xferr the rest of the hardware from the dell to the new unit.  The cost would probably be about the same and in the end you would end up with a superior machine to the 4600.

    I got lucky though the new PSU fixed my problem.

  • Check this out, found it on another thread:

  • Yes, I've considered switching the CPUs to try to isolate if it's the motherboard or the CPU.

    I've never taken a P4 out before and was nervous that I'd damage something.  Most instructions I see have folks doing it without the heatsink installed.  Can I do it without having to remove the heatsinks or is removing and reapplying the heatsink no big deal?

    Are there instructions specific to this type of socket/motherboard?

    Finally, if I do get a different brand of ATX/P4 motherboard, would have to re-format/reload Windows and everything on my hard disk for the new motherboard/bios?



  • burnboy.
    How to remove and replace the processor and heatsink in the D-4600
    You will need to replace the thermal seal between the heatsink and processor. Use Arctic Silver 5.
    D-4600 Diagnostic Lights


    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • Thanks for the tips.  I swapped the CPU and RAM with the good 4600 and they worked, so now I'm basically down to the motherboard.  Looks like that's the bad component... so off to finding a good price on motherboard replacement.


    Steven (aka burnboy)

  • burnboy.
    Thank's for the feedback.
    For a replacement D-4600 motherboard, browse eBay, or call Dell Spare Parts @ 1-800-357-3355 option 4, M-F 7 to 7 CDT and have the system's "Service Tag" handy.


    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell