Ran into an interesting problem today regarding an Intel motherboard, BIOS and some CPU’s.

First the hardware involved:

• Intel DZ68BC motherboard
• Intel i5 Ivy Bridge CPU

The symptoms:

• Three long beeps when motherboard is powered on
• POST error code 15
• No BIOS screen available, no video output at all

The cause:

The DZ68BC motherboard with a BIOS version of 0021 is not compatible with the Ivy Bridge architecture.

Some DZ68BC’s do come with newer BIOS versions which should (in theory) be able to handle the Ivy Bridge line, but the one I had came with version 0021.

The solution:

Luckily I had a Sandy Bridge CPU in the shop. It was an i3 but that didn’t matter. I put that processor in the board, and flashed the BIOS via USB to version 0028. Everything went fine.

Then I flashed the BIOS via USB to version 0035. Everything still fine.

Flashed the BIOS via USB to version 0037 which resulted in a non-functional system. At this point I was back where I started; no video output, no signs of a functioning BIOS at all.

I tried rolling back the BIOS to an earlier version, this (obviously) did not work.

Fortunately my co-worker had an idea that escaped me. He moved the single stick of RAM from DIMM slot 1 to another slot. In this case he moved it to slot 3 and all of a sudden the computer was functional again. Also, the BIOS was indeed version 0037. The OS was then able to be installed as normal, with the Ivy Bridge i5 in place.

The Conclusion:

Why switching the slot the RAM was in made any difference whatsoever is unknown to me at this point. What is obvious though, is that reverting back to a 2nd generation i-series processor was essential in getting this motherboard up to the correct BIOS version to allow the use of a 3rd generation Ivy Bridge processor.