White screen on a Franken-iMac - can't boot
Greetings from Bulgaria. I’m new to this, so please bear with me. I recently bought two 27” iMacs mid-2011 (A1312) with missing parts in order to try and build one working computer for my wife to use (bought them separately from flea markets - 60 USD in total after haggling). The iMacs are the same model - only the CPU and the GFX cards are different (one is i5 and the other is i7). I know that there is a great chance that some of the parts are faulty and I don’t know the history of the machines and why they ended up in a flea market, but it is my tiny project and I want to do my best to make it work.
I took all the good parts and combined them into one machine. Тhe display cable connecting to the logic board is the only broken link, but I’ve already ordered a new one and waiting for it to arrive. For the time being I am using an external display to check if the system is working. I installed 8 Gb RAM and an SSD I had lying around. There is no OS on it, but I have an old DVD of Mountain Lion which I intend to install. The system does not boot though - even from the DVD.
I hear the chime and LED 1, 2 and 3 light up. This means that there is power and the logic board communicates with the GFX card (dare I assume that there is no problem with them?). The screen is white-grey with vertical stripes.
I tried resetting the PRAM (Holding cmd+opt+P+R) - it restarts, but nothing changes. 15 seconds after the power is on, the fans start spinning at 100% but I assume that it is because of the missing thermal sensor on the HDD - the one on the optical drive is there (I intend to buy a cable with sensor but for the time being it should work without it too). I am not sure about the origin of the problem.
My next step will be to swap the GFX card with the one from the other iMac, but I would be very grateful if you share your experience with me. Any advice is more than welcome.
Es esta una buena pregunta?