So, my thought is that you issue is unlikely to be a direct result of having a different VBIOS. If the GPU installed now is supported by the PCI revision onboard, it should support the GPU regardless of the VBIOS version being different than the original.
How did the previous GPU get "fried"? Chances are something else may have been damaged as well, or that the problem wasn't the other GPU to start with. I begin by seeing if there is an updated BIOS for your laptop model. If so, install it. If not, I'd contact your laptop manufacturer to verify the new GPU should work with your unit or if there is some reason the hardware is unsupported.
Before doing that though, you might try removing the battery (With the new GPU installed) and disconnecting the power cable. Press the power button for about sixty seconds then reinstall the main battery and AC/charging cable. Try power on and pressing whatever key is normally necessary to load the BIOS and reset the bios to optimal defaults.
Clearing the BIOS in this way may allow the new hardware to be recognized. You might also try removing or unplugging the CMOS battery while observing the above method with the power cable and battery removed to reset the BIOS to clear all default hardware configurations.
I did sent my laptop to diagnostics from where i got an answer that my gpu is indeed done(although they said that there is a slight chanche that the cpu might be damaged as well but its a rare thing. It didnt even boot up while having that old gpu in it.
Well, I'd say there's a good chance that you're one of the "rare things" that in my experience really isn't all that rare at all. More often than not, if there is an issue with power distribution due to a faulty power jack or AC adapter, or something else that causes a short circuit or spike in internal voltage, it's not uncommon for multiple components to be affected. Also, if the GPU was damaged by exceeding thermal limits, it's equally possible for the CPU to have been damaged as well.
It's also quite possible that the GPU fried due to a lack of cooling from a fan failure. Are you hearing ANY fans come on when you attempt to power up? Does you unit have more than one internal fan, as in, one for the CPU and a separate fan for the GPU? If so, are they both coming on at boot like they should normally do? If there is a fan or fans that are not working it could easily result in thermal damage to the GPU or CPU and if the fan has failed completely and no reference signal indicating RPM is being received by the BIOS then it's likely it won't allow the system to boot. Many systems, desktops and laptops both, wont' boot at all if no fan reference signal is detected within the first second or less of power state management.
It's equally possible that there is an issue with the motherboard's PCI circuit, which if a short circuit condition occurs or exists, could easily damage CPUs, GPUs, and other devices that communicate over the PCI bus.
I assembled the new GPU after the older GPU was removed by the guys from diagnostics (although before all that when i was trying to find the issue i did remove/assemble it couple of times, but with care. Model number : NKP150HM0001F00142
I'd suggest you start by contacting Sager at the email address listed on the following link and ask them to provide you with an updated BIOS as well as instructions on how to update it considering your inability to see anything. I'm almost certain the issue is related to the hardware being newer than the current BIOS has support for.
well i wrote them few days ago and these are their answers :
1st: The new gtx485m must be for the same P150HM notebook model, if that GPU came from a different notebook model then the GPU VBIOS is different, but we don’t have the VBIOS for the GPU.
2nd: Sorry can’t help, some of the unit have two GPU slot, then it can put the new GPU on the 2nd GPU slot and flash the right BIOS to the new GPU, but if the unit only can put one GPU then is difficult, which we don’t know how to do it.
What i'm trying to know here is that is it even theoretically possible to make my gpu to talk with my laptop. Is there ways to match that vbios somehow to my bios or vice versa. I don't really want to waste my money to diagnostics if its not possible.
This is what happens when you buy from a custom builder. It's why I don't recommend it. I always recommend sticking to OEM units as the customer support is MUCH better and you don't run into these issues. You're going to have to look around the mod forums for a modified VBIOS maybe.
That unit should also have integrated graphics on the i7 and if you can change to that in the BIOS you should be able to at least get the unit working. I'd try removing the GPU and seeing if the display works then. If not, try removing or unplugging the CMOS battery for thirty seconds with it disconnected from power and the battery and GPU card removed, then put it all back except the GPU card and try to boot.