Bizarre behaviour of 2720QM ES CPU and M4600.

Recently I bought a 2720QM ES on ebay to upgrade the dual core cpu of my M4600 but apparently there is some sort of conflict with the video signal because the display won't turn on. At the beginning I thought that the machine didn't boot at all because the processor may be damaged but after a few seconds I could hear the windows login sound . Then I messed with the optimus option . By default it came disabled in BIOS . After enabling optimus I rebooted the machine and could see the dell logo. The problem is for some reason the system disables again optimus after turning off the machine so I get the same initial problem again, no video signal. Is the cpu defective or it's just an ES so there may be some kind of incompatiblity with optimus ?

 

If by chance did you disconnect the CMOS battery from the motherboard?

Is any other settings reverted to default...?

Did you disconnect the GPU by any chance? Cause having optimus disabled will use the PCI-E slot for GPU (Nvidia) for video output, having optimus enabled will use the Intel GPU and Nvidia GPU. Can you still see the Nvidia GPU when having optimus enabled?

 

If the display is working in the Bios then it is very likely that you have everything hooked up correctly & that the hardware is functioning. That would lead me to think there is a driver / software issue causing the problem. You could try hooking up an external monitor if you have access to one (most modern tv's have a vga connector as well) to see if it works. If it does you can start troubleshooting.

 

I didn't disconnect the CMOS battery nor the GPU, just replaced the processor . It's the system that when the 2720QM is installed automatically after each reboot switchs back to optimus disabled .If I install again the old cpu ( i7 2620) everything works fine, so I suspect I got a buggy ES cpu. Now that you mention about disconnecting the GPU I wondered what would happen in that case. I pulled the nvidia card and the system boots normally displaying the dell logo and the windows splash screen, but after that, at the login screen the image starts flikering like mad. I managed to stabilize it changing some options in the control panel like lowering refresh rate from 60 to 40Hz. latest HD3000 drivers are installed. At least with the nvidia card uninstalled I can reboot and the lcd will display the video signal . By the way I tried with different versions of BIOS but didn't help.

 

No, the display does not show any signal even at boot time.Only if optimus is enabled the screen displays the video signal normally. To enable optimus I put the old processor that came with the laptop and enter the BIOS menu, then I switch to the 2720QM and boot the system. The problem is if I boot once again the system shows a message like "the cpu has changed, to install it press Y . Some options will be disabled" . In fact it disables optimus and without optimus enabled I get no video signal again, but the machine boots normally because I can hear the windows login sound.