I've acquired a Dell precision laptop (I believe it's an M4600; the bottom of the machine just says "P13F").
I bought it yesterday for $50. When powered on, the display backlight illuminates, but does not show any picture. In fact, the machine actually booted when I tested it yesterday, but the display never came on. The keyboard backlight came on, and I heard the "ding" of Windows 7 logging in, but no picture ever came up. I followed a disassembly guide and cleaned/re-seated the LVDS connector (is that the correct piece?), but to no avail. I went ahead and ordered a replacement screen, but now I'm thinking it may be the gpu instead. I plugged in displays to the 3 video out ports on the machine, and couldn't get any output on those either, though the machine was admittedly still taken apart, so perhaps that kept it from working.
Does anyone have similar experience with a laptop display; i.e., display powers on, backlight activates, and even goes off/on but with no picture, not even POST?
Normally computers will not boot up if the GPU is broken, so you wouldn't have heard the beep of Windows.
Sometimes on laptops, you will need to use the keyboard shortcut to tell it to output video.
Yes, and it was the display last time it happened to me.
The M4600 has the option of a dedicated GPU, and can be removed/upgraded. If you think it is the GPU which is it fault, remove it. However, I must warn you, taking apart that laptop is a B1tch, and I'm not even sure if the laptop would boot without the dedicated GPU, but it's worth a shot if you think that is the issue.
I also don't think the laptop uses the dedicated GPU when booting; I'm fairly sure that it uses the integrated GPU in the CPU.
Twas the GPU. I replaced the screen, to no avail, but pulling the GPU out and powering up gave me a successful boot on the igpu. Now, I only wish I'd gotten as far as pulling it before ordering a new screen and waiting for it to ship in.
I guess I'll order a new video card and see how it goes. Also, I could stand to give the old one a connector cleaning and one last try.
I replaced the video card with an AMD M4000. Same issue, though. No video output, at all. If I remove it, the igpu once again works. I am trying to update bios, which of course only comes packaged as a .exe file. FreeDOS wouldn't run it, so I'm going to boot a Windows installer and see if the installer will run the bios updater. I'm not expecting it to fix my issue, but it's worth a try.
It's looking more like the last gpu may have taken out something else in its path, though it could be that this replacement is a dud. I may have to settle permanently for onboard graphics.
I got the bios updated, but no dice. I even did some crazy things like, uh... Plugging in the card while the system is booted. It powered off immediately, and gave me a message next boot about the temp alarm being tripped. This leads me to believe there may be some electrical loop somewhere that is tripped when a card is plugged in. I mean, honestly, i have no idea what I'm doing, here, so it's my best guess.
It's worth noting that the gpu heatsink does become noticeably warm to the touch when the card is installed and the system is powered. Still no external video output at all.
Bad mobo is starting to sound likely to me, but there's no easy way to test that without specialized equipment afaik. You could try using the laptop with the iGPU, and see if it randomly dies on you. If it does, there's not much left in the laptop that could be broken. If the laptop works, though, then it's hard to say.
It's possible that whatever blew on your old GPU took out part of the mobo with it.
Everything works fine with the igpu. That is what puzzles me. The old dgpu left some black crap on the motherboard, which I cleaned with alcohol and re-sealed with e-tape (there was a protective layer that it burned through). All the carbonized shit came off, and it doesn't appear to have left any residual visual damage to the traces. Tomorrow, I'll try inspecting and cleaning it again.
I know this is kinda late but I just made an account to say this that Yes the issue was The Gpu. I have the same exact model and also the same exact problem. laptop booting absolutely fine with just no display, lcd basically wont even turn on. Saw your post, pulled the gpu out and finally got the display back on Intel. however my gpu didnt have any damage marks on it. also there was no way to fit the heatsink as it was screwed over the gpu so now one fan is doing absolutely nothing in the laptop. anyway Thanks!
