Installing GPU with an APU?

Ok, so I understand that if I install a dedicated GPU, the APU should disable itself. My question is, are there any drivers I need to remove?

No. Most likely you will have to installed drivers for your new GPU.

Some motherboards are stubborn on what it uses to drive the display, so it is possible that the APU is not disabled and uses the GPU as a passthrough until you hit up the BIOS and change it.

You can be extra sure by putting primary display adapter to pci from bios.

Depending...
If you use Windows 10 and amd gpu, then you can use both. If you have Nvidia Gpu you will use only it, no matter what.
Also I believe if you install an Nvidia gpu, you will have to remove catalyst drivers...
Win7 and Win8/8.1 - only the discrete GPU...

I have first hand experience with this.

What discrete GPU are you adding? Is it from AMD or Nvidia?

It's an AMD card and the PC is running Windows 7.

It should just be a matter of moving your video output from your motherboard ports to the ports on your GPU. You may have to disable integrated graphics in your BIOS. Beyond that, it should be just a matter of booting into windows and letting windows detect the hardware, and doing another reboot. It should work as normal after that.

At worst, you'll have to do a reinstall of your video drivers.

Well I just realized that the PC I was going to put this GPU in only has a 300w PSU. The GPU is an MSI r7770. I think that is too low to take the risk. This is my uncle's PC we are talking about here and it is a new PC. He needed a new one but would not let me build him one because he wanted it ready to go as soon as it came in from newegg. This is the PC I ordered him,

http://www.newegg.com/Product/Product.aspx?Item=N82E16883220837

He only needed a basic PC really so I thought this was a decent PC and I was going to put the r7770 in it for some gaming when I'm over there. Any GPUs out there that only require a 300w PSU that aren't terrible?

Anyone?

I'm not sure I would trust any 300 watt OEM PSU with something that may be beyond its capacity.

Actually, I checked here and there, and I don't think the total system power draw will be more than 260W. Even if the PSU is not the greatest, I don't really think there will be much of a problem. I mean the CPU is not power hungry at all, the GPU is not either. Even if we count a peak 100% cpu and GPU, it should be around 250-260 watt.

But would you trust such a PSU to run with a great than 80% load?

Me? i bought 430W Seasonic instead of 500W other branded for the quality, so honestly, i don't know. If i had a PSU i would not have bought the Seasonic. So may be yes, i don't know. In that situation i would probably just install the gpu. It would be used once in a while, and my guess is it is not gona run Metro Last Light on ultra... So i would most likely not change the PSU. If i was building this system, i would not have chosen that kind of psu, but since we already have it...

I just really don't want to damage anything since the PC is under warranty. If it wasn't, I would try the GPU without hesitation.

Do you have the gpu, or you are going to be buying it? If you're buying it, try looking for something like GTX750... It only uses the Pci-e power and I think is actually better than 7770. May be take a look at some second hand 750s... Since the PSU is the limiting factor, may be sell this card and get 750. However, then you would have to remove the amd drivers completely, God know what will the Nvidia drivers do to them.

You don't use windows 10, windows 10 uses you.