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Device repair and information for the Dell Alienware 15 R3, a gaming laptop in the Alienware series.

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Display not working & CPU overheating

Hello everyone,

I have an Alienware 15 R3 (i7-6700HQ & GTX 1070). Recently my laptop would overheat and its idle temp would be 92 C. I opened up the laptop repasted the GPU and CPU with arctic mx-4 and after the assembly the display wouldn’t work. The display works when booting with D + Power button and flashes all colors correctly. When connecting with an exterior monitor via HDMI the lcd display doesn’t show anything yet the external monitor works fine. The LCD display is not completely dim it emits some sort of light yet shows nothing. And unfortunately my idle temps even though it dropped to 80 is still too high i think for idle temps. I even undervolted the CPU and still the temps are that high.

How can i diagnose the issue with the LCD (I speculate it’s either the LCD cable or the cable’s socket on the motherboard) ?

Why are my idle temps this high and is this normal ?

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Are both the fans working, you didn't say?

Did you try toggling the graphics between integrated and discrete by pressing Fn + F7 just to check?

Also try operating Fn + F10 to increase the screen brightness.

Just trying to eliminate remote possibilities.

You say that the display emits some sort of light so try shining a torch at an angle close to the laptop screen and check for images when the laptop is on and there is a display on the external monitor. Try this in a darkened room because if there are any images, they will be very faint.

If there are images is then there is a backlight problem. You would need to know the pinout for the video cable to know which pins the backlight feed is on. Mostly in laptops the backlight power is permanently supplied to the LCD panel and it is turned on and off in the panel by a signal from the motherboard on the BL_On wire in the video cable.

If there are no images then as you say there most probably is a connection problem but it could be at either end, motherboard or LCD panel or perhaps the cable is damaged where it passes through the hinge to get to the panel from the motherboard

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Thank you for your time. Yes both fans are working and spinning at around 4k rpm each (based on hwinfo64).Toggling graphics did not work and the screen brightness is already at its maximum. The LCD backlight is working but there is no video (shining the torch showed nothing). I guess as i didn't go near the LCD panel itself, the issue is either on the motherboard or the cable. Is there anyway i could figure out were exactly the issue is ? And if so happens that issue was on the motherboard is there any way i could fix it instead of replacing the motherboard ?


Hi @ georges dimitry ,

The fans spinning at maximum is a worry as this suggests that something is overheating. Also the backlight being on but no video as you say suggests a video problem but since there is an external display the GPU (both of them?) are OK.

There may be nothing for it except to first check the video cable at both ends and if it seems secure to replace the cable and then check if the display works.

If it does then there is still the overheating issue which maybe a faulty temp sensor but this is only a guess.

Try searching online for "(insert motherboard 'board number') schematics" to hopefully find the schematics for the motherboard.

The sensors should be shown in the schematics.

Do the fans run high when the laptop is started in safe mode or if you go into BIOS?

I realize that BIOS will be hard because there will be no display but I'm just trying to narrow it down to a software or a hardware problem.

If it also happens when "in" BIOS then most probably it is hardware.

Just as a far out idea, disconnect and test the coin cell cmos battery in the laptop.

Here's the service manual go to p.46.

If it is <2.6V DC replace it.

Also do a power refresh.

Disconnect charger (if connected) disconnect main battery, disconnect coin cell battery and then press and hold the laptop's power button for 30 seconds then release. Reconnect in the reverse order and start the laptop and check what happens with the fans

This will restore the BIOS to defaults in case there are any corrupted settings that may be causing the BIOS to malfunction.

Worth a try anyway.



Just another thought on the video problem.

Did you disconnect the main battery from the motherboard when you refreshed the thermal paste on the CPU / GPU? Hopefully you did.


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georges dimitry will be eternally grateful.
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