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Dell OptiPlex 755 SFF Diagnostic Lights Not Working
I put in a brand new Dell OEM mothererboard in my Dell OptiPlex 755 SFF since the last one failed. I used a board that was the same part number, but a A01 revision instead of a A00. I did put in the correct configuration as what is says on the side panel. The new one has the A12 BIOS, I can't update it until I get a hard drive for the computer and install an operating system. The new one works perfectly except for the diagnostic lights. The power button works along with the power light (And it can go between green and amber depending on the situation). Also, the disk activity and LAN light work like they should. But the 1 2 3 4 diagnostic lights never light up. Not when booting up, nor when I remove the memory modules to cause an error. I couldn't find anything in the BIOS. I checked the cables that go from the motherboard to the front panel circuit board and the cable that goes from the front panel board to the diagnostic lights and both seem to be okay. The front panel circuit board also appears to be okay. The onboard diagnostics show no problems except for the missing hard drive. Anyway, how can I fix the diagnostic lights?
DELL-Chris M
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November 28th, 2016 08:00
The 755 came out in 2007, so I doubt that the replacement 755 motherboard is new. Did you replace the CMOS battery on it? I have never heard of the LEDs just not working. I take it that they worked with the prior motherboard? Assuming you reseated the cabling on both ends. Without memory installed, were there any beep codes?
Appleboy45
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November 28th, 2016 13:00
There was a beep code. The motherboard I bought on eBay, it appears to be new since it had no service tag (But maybe someone could have cleared it somehow), but there is no real way to know.
DELL-Chris M
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November 29th, 2016 05:00
My point was that there would not have been any motherboards manufactured for this 2007 PC after 2010. So the one you purchased was refurbished/used.
Optiplex 755 beep codes
Appleboy45
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December 15th, 2016 15:00
There is new old stock on eBay. So that's how I got it new. I know it's not the best idea, but the coward works at least. Do you know if there is a way you can check it is genuine with the serial number, even though it appears to be genuine.
speedstep
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December 16th, 2016 04:00
There aren't any fake 10 year old dell motherboards that I know of. I would never buy a bare board for the simple reason that 620 745 755 760 780's are all very inexpensive now. Not a board but the whole thing. And you can get them from Amazon and Walmart and microcenter etc. 745's and 755's came with XP or Vista. They have windows 7 and a computer for the price of windows.
https://www.walmart.com/ip/40660522