Is it possible to boot without a GPU (graphics card)? Yes, but...

Recently, I changed my CPU from a Celeron 530, which had an integrated GPU, to Xeon E3-1230v2 which lacks one. Of course I was going to use it on my home server, which does not have a monitor connected to it. But the computer did not boot. I had never expected that.

Only Asrock supports it, with their customer support

My mainboard is an Asrock B75 Pro3-M. I contacted Asrock support. One of the engineers replied to me; what the reply read was essentially, all "normal bios" on Asrock motherboards require a GPU to boot, but he would find a way for me. After a few days later, yesterday, I received a modified bios from him. I flashed it on my mainboard and it booted without a GPU!

Meanwhile, I have also contacted all major mainboard manufacturers, MSI, Gigabyte, Asus, asking if they have any models that support booting without a GPU. Their replies were all the same:
"A GPU is required to boot, we do not have any model that can boot without a GPU."

Personally I think Asrock's support (reply) was the most humane and friendly. And their mainboards are also very stable and feature-packed. I will choose Asrock again next time, if I am to choose one from similar mainboards from various manufacturers.

What about OS?

Now the mainboard booted without a GPU, what about the OS? This, too, was what I did not expect.

Windows = YES (BIOS) and NO (UEFI)

Well, I found that Windows 7, Windows 8.1 and Windows Server 2012 R2 (even if it is a Server Core version) cannot boot in UEFI mode without a GPU. Of course I could not see what was wrong because there was no graphics output, but I knew it because when the OS recognises my onboard Ethernet, its light turns green and when I booted to UEFI mode Windows without a GPU, it did not turn green.

Luckily all Windows 7, 8.1 and Server 2012 R2 booted successfully without any GPU when they were installed in the traditional BIOS mode. As far as I know what you get from UEFI mode are

• Boot disk can be 3TB or larger
• Secure Boot

,not any performance enhancements. Well I do not need any of the UEFI advantages, so I am OK with the BIOS mode Windows.

Ubuntu = YES, but NO GUI

Then I tried Ubuntu Server 12.04. It booted successfully and I could connect to it using SSH or HTTP. What about Ubuntu Desktop 12.04? It seemed to be booted, because I could connect to it using SSH, but I think it failed to log into GUI. Because when it is logged in, I should be able to connect to it using VNC, but I could not. I am not so good at Linux so maybe there could be a way to log into GUI without a GPU, but I decided not to waste my time trying to figure it out; it was not time-effective.

ESXi = YES

Since it has no GUI whatsoever, it just booted normally, as expected. I could even run Windows 7 on it with Aero. It seems ESXi can emulate GPU without a real GPU. As far as I remember, the Aero experience index was about 4.5 and the 3D gaming experience index was about 3. So Aero ran fine.