[How To] Using a LGA 771 Xeon in a LGA 775 motherboard AKA 771 mod

omega552003 · May 9, 2015

Let me preface this with that I haven't personally done it. I have read a good deal into this because I was going to do it when I saw the prices of 771 Xeons especially the X54## series compared to similar Core2Quads of similar pricing. 771 Xeons are dirt cheap right now due to their usefulness in the industry being non existent. For comparison, a Core2Extreme QX9770 @ 3.2Ghz with 12MB of L2 for $249 and a Xeon X5482 @ 3.2Ghz with 12mb of L2 goes for $54usd. I know that this is an old platform, but people do still use the 775 platform for gaming, I have a friend that is using a Core2Quad Q8200 with a GTX 770. So I hope this helps someone especially when looking for an 775 upgrade on the cheap.

To do this mod you need to understand what the differences between the 771 and 775 cpus. The 771 and 775 are the %99.2 exactly the same pin out, only difference is the 4 missing pins for the 771 and 2 pins that are flipped. The good new is that the 2 flipped pins are next to each other and a simple sticker can switch them.

Now the other thing that is different is the orientation key is 90 degrees rotated to so you must modify the 775 CPU socket to remove the alignment tabs so you can rotate the 771 CPU into the correct orientation.

Lastly most 775 motherboards don't have the microcode to identify the Xeon CPU in the BIOS, some do because of programer laziness and they just put all possible combinations to ensure that it would work for future 775 CPUs, while others have only programmed in known 775 CPU microcode.

Heres some info on it:

General mod overview and guides:

http://www.overclock.net/t/1384920/good-news-for-the-lga775-now-771-is-available-to-convert-to-775-motherboard

http://www.overclock.net/t/1431723/mod-lga775-support-for-lga771-xeon-cpus

http://www.delidded.com/lga-771-to-775-adapter/

Specifics on Microcode updating:

http://www.delidded.com/how-to-update-cpu-microcode-in-award-or-phoenix-bios/

http://www.delidded.com/how-to-update-cpu-microcode-in-ami-bios/

http://www.delidded.com/lga-771-xeon-microcode/

Bonus 771 Xeon overclocking even for server boards!:

http://forums.2cpu.com/showthread.php?t=77937