Dell Latitude E6540 AC Adapter Not Recognized Error

Hello,
I was given a laptop from work that was free. However, I'm having issues with getting it working properly. When booting up it gives an error message that the AC adapter isn't recognized. (As seen in the BIOS and the boot up screen) I've done some pretty extensive things getting this thing working as it's a fairly decent machine when it's working right. When I bypass the error message (By pressing F2) The system boots, however it's severely throttled. The CPU is at a constant 800 MHz and the Video card is locked to 300 MHz (I think). I can use ThrottleStop to unlock the Throttle control to get the CPU back up to the normal 2.8 GHz, however 2 things happen when I use this software. 1 is that I notice that Turbo boost doesn't work as the CPU wont actually clock above 2.7 GHz, 2. Is while the CPU might be unthrottled, the GPU (AMD Radeon 8790M) is still throttled
somehow.
The machine in question is a
Dell Latitude E6540 (Intel i7 4810MQ, 8GB DDR3 RAM, AMD RADEON HD 8790M 2GB DDR5, 1TB Hybrid HD, 1080p IPS LED)
I'm starting to believe that the underlying problem has to do with the motherboard itself.

Here's what I've tried so far;
-Updated the BIOS from A08 to A17. (using /forceit command) Newest Release from Dell Website.
-I've purchased a NEW AC Adapter (130 W that matches the Dell P/N from the adapter that came with the machine.)
-I've purchased a New Docking station thinking that I could charge though the dock instead of a possible damaged AC plug on the side of the machine. Powers on and almost shuts off immediately.
-Purchased New DDR 3 RAM
-Purchased New Hard Drive
-Purchased New Internal AC Plug
-Purchased New Battery for the hell of it.
(One thing I noticed is that the battery was 1/2 charged when I received it from Dell. When working only off the battery the computer instantly came to life and was really fast without issues, however the battery is at 0% now..drained it without the adapter.)

When the battery (even though it's dead) is inserted with the AC adapter plugged in, the computer boots, however in Windows it doesn't charge. It'll show 0% available and 1675:00 Hours Remaining and the computer will work flawlessly even though the AC adapter is still unrecognized.
Is it possible to use throttlestop and unthrottle both the CPU and the GPU (I've already tried MSI Afterburner which doesn't help? Or if not, I guess the only way to get full power from this machine is too have the battery dead and at 0% with the new power adapter connected. Also,

Rise of the Triad Benchmark @ High Settings at 720P

-With AC Adapter and No Battery (No ThrottleStop) : 2 FPS (800 MHz CPU Clock / 300 MHz GPU Clock)
-With No AC Adapter and with Battery(No ThrottleStop): : 68 FPS (3.72 GHz CPU Clock / 900 MHz GPU Clock)
-With AC Adapter and with Battery (No ThrottleStop) : 62 FPS (3.72 GHz CPU Clock / 900 MHz GPU Clock)
- With Ac Adapter and No Battery (With ThrottleStop) : 25 FPS ( 2.68 GHz Clock / 300 MHz GPU Clock)
-With Dock -No Post on Boot-
*Also I cannot get the battery charge at all, even with and without the dock.


I feel that running this way isn't really practical...
Any help would be appreciated!

Thank You for Reading

 

Well i think you pretty much done all the steps you could do, It does seem the problem is with the motherboard.
the charge circuit is usually fuse protected and it possible it has blown.
If your technical enough you can try to see if you can find the DC/DC circuit and maybe isolate the fault
You already spent a few $$$ so really up to you to decide how much more money you want to put into this laptop

 

Yes, I definitely agree! I was hoping if anything I might be able to use this laptop with the AC adapter only, provided that it works properly. However, since it doesn't I can use ThrottleStop for the CPU, however the GPU seems to still be throttled. Thank You for the Reply!

 

I'd get the motherboard replaced ASAP, 0% charge is absolute hell for lithium based batteries. Dell AC adapters are special as they have a comm pin in the center of the barrel connector. If you can run the laptop at 0% battery, it means you are actually getting power (thus adapter output and main power rails are fine). The reason why your machine isn't charging is because Dell has designed their battery charging circuitry to only charge if the power brick is from Dell (model # doesn't actually matter that much as long as it is at equal or greater wattage specifications than the original).

TLDR: Replace the motherboard!