Odd Compatibility Issue Between MB and GPU

[A_Random_Guy]

Hey there everyone!
I've had an unfortunate accident where I broke my CPU fan/cooler (finger slipped and touched a fin), which made it shake violently and broke/bent pins on my old PC's socket.
I tried fixing it and I just gave up on it. In the dump goes the Unika AK42-D.

Specs are as follow :
MB : Unika AK42-D (LGA 775 socket)
CPU : Intel Core 2 Quad Q9300 (Not OC'ed)
RAM : 6Gb of DDR2
GPU : AMD Radeon's HIS HD 7950 w/ 3Gb of GDDR5 (Not OC'ed)
SSD : No name Chinese brand, 240gb (Kingspec?)
HDD : 1.5 TB from Seagate

With that in mind, I went around looking for another LGA 775 board and found a mint-condition DG33FB from Intel. I got it for a cheap price and it seemed like the PERFECT candidate to replace my older MB. I had it installed where my old one stood and wired it up.
Everything was fine when testing with RAM, HDD's and SSD's connected. It booted up and I got the hardware drivers installed again (getting headphones and mics recognised + organised again).
Last step was adding my GPU into the set. Got it wired and booted it up. It would POST, but...
It just stays on the first screen where it tells me to "Press F2 to enter BOOT/BIOS" or something among the lines. Every key press is answered by a beeping coming from the motherboard.
Just under the "Press F2" message's displayed what I guess is an error code "5A".

Now, I've done some bit or research about the error code and it's linked to SATA ports.
Paradoxically, all SATA ports are functional ONLY when the GPU is absent.
I'm really bummed by this issue and I have no idea how to deal with it.
Are my days of gaming come to an end until I save up enough for a newer PC?
I'm reluctant about giving up on this old build of mine.

TL;DR : Changed motherboard to an Intel DG33FB, hardware's all the same (specs above), won't boot when GPU (HD 7950) is plugged in. Error Code 5A appears and KB beeps when pressed.
Meaning keystrokes are recognised and PC understands, but won't proceed with an error present. Absence of GPU when connecting to MB's VGA presents no issues.

 

[cin19]

Meaning keystrokes are recognised and PC understands, but won't proceed with an error present. Absence of GPU when connecting to MB's VGA presents no issues.

1) Do you test the hd7950 in other PC? make sure it works
2) What PSU do you have? assuming it is fine because you used. Try other PSU if you have one.
3) May update the BIOS or chipset from intel site.
4) Because you can use the pc with onboard iGPU, that means either the MB pcie slot, gpu, or PSU has problem. That why recommend to do those things.

 

[A_Random_Guy]

1)The HD 7950 worked the day before and even the fan's running on them. When I boot open my PC, it shows the screen through the card to the monitor, meaning it's working and connected.

2) It's an Antec 500w one. It worked with everything I have, newer or older motherboard.

3) Since the DG33FB is no longer supported, as it dates back from like the 07~09 era. BIOS is up to date, I got the most recent one. Actually tempted to downgrade to a previous one.

4) PSU + GPU never had issues, so that's ruled out. I'm really afraid of having the MB PCIE slot not accepting the card, although it lets info through (Like I said, the PC boots and shows me the screen where I need to press F2 to get into BIOS, but doesn't let me though as the MB beeps at every key press.)

I know, it's a really complex issue.
I'll try an older ASUS GTX 660 ti to see if it would work with that one instead. It'll be a bummer though.

 

[cin19]

Yes, try other GPU.
I don't know the MB has the UEFI BIOS or not, maybe not. In case it does, and you use win8/win10, may try disable secure boot, and use the legacy boot.

 

[A_Random_Guy]

I'm not so tech savvy when it comes to BIOS and all, but I don't think my old MB has UEFI BIOS.
Also, I forgot to mention I'm running on Windows 7 Ult. 64 bit, sorry.

 

[cin19]

Do you try the other GPU? what happens? works or not.

 

[A_Random_Guy]

Do you try the other GPU? what happens? works or not.

I'll do so when I'll be back home. Thanks for the suggestion!
If it doesn't work, then I'll be perplexed and lost.

 

[A_Random_Guy]

Got home, changed the GPU from my HD 7950 down to my 660Ti, it works.
Sadly, it seems like any Intel MB from the LGA 775-era don't like AMD cards, as I've read from forums.
Hypothetical conclusion : the DG33FB doesn't work/isn't compatible with the Radeon HD series.

 

[cin19]

That maybe like the old topic. That MB has G33 chipset, which has the pcie1.1X16. And If the MB does not have the newer BIOS at least after 2009. And the MB will have compatibility problem with AMD pcie3.0 GPU only, someone did the test and had the result. The final answer to the controversial PCIe x16 version compatibility. http://www.overclock.net/a/the-final-answer-to-the-controversial-pcie-x16-version-compatibility

 

[A_Random_Guy]

Well, switching back to NVIDIA did solve the problem, but it's just sad to know that it's all because of the Chipset's fault the it doesn't work.
I thought I was safe looking at the Intel Ark's page of the MB.
Oh well, thanks for all the help and all the info, that's a relief to know why it doesn't work.
I might think of returning the MB and looking for another one, since I really like my HD 7950.