[MOD] LGA771 to LGA775 CPU modification tutorial

[harrynowl]

Hi. This is a quick guide on modding your LGA771 CPU into a fully LGA775 compatible state, we'll cover why you'd want to do this later. I'll start with the basics.

 

Difficulty: Intermediate

Do not attempt this mod if you aren't comfortable with working near the CPU socket or performing basic BIOS modifications.

 

Disclaimer:

I'm not responsible for any damage to you and/or your equipment whilst performing this modification, you proceed at your own discretion.

 

Tools required:

 

Razor blade (sharper the better):

 

Additional items:

 

Compatible motherboard

The fastest way to check compatibility is by chipset. Commonly compatible chipsets include. It is worth searching for your specific motherboard online to see if anyone has done it before:

 

G31*

P35

G41

P45

650i

680i**

780i

 

* Not all G31 chipsets are capable of running 1333MHz FSB AND/OR 45nm CPUs - please check compatibility with similar CPUs such as the Q9650 before buying anything!

 

** nForce 680i had issues running Quad Core CPUs with a 1333MHz FSB. If your board is 680i please note the CPU may not be stable at default frequencies.

 

X48, Q35 and Q45 chipsets do not work with this mod. Most Intel reference boards are not compatible. X38 can sometimes be compatible but is often not.

 

Chosen CPU

So the CPU is quite an important choice, you now have the option to use Xeons which are more or less identical to the consumer parts. If you're doing this mod you should probably look at the Quad cores as dual core 775 CPUs are cheap, the Xeon quads are usually considerably cheaper than the 775 Core 2 Quads.

 

Popular choices:

E5450/X5450 - 3GHz 1333FSB

X5460 - 3.16GHz 1333FSB

X5470 - 3.3GHz 1333FSB

 

To see all available CPUs please read this great list from delidded.com.

 

Modification sticker

 

To perform this modification you need a sticker to swap 2 pins around, as the only difference between the LGA775 and 771 pinout is they swapped two of the pins, a simple sticker can undo this change.

These stickers can be found cheap on eBay.

 

How to apply the sticker correctly

The sticker is pretty straightforward to apply, on your CPU identify which side has the golden triangle that tells how how to orientate it in the socket, there is also a triangle on the base. After you've done that you need to place the sticker over the 11th and 12th row left of the triangle on the CPU.

 

If you have applied your sticker correctly it should look like this

 

Once you've applied your sticker, you can move to the next step.

 

Physical differences

OK so another difference between the LGA775 and LGA771 CPUs is the tab location on the CPU is different, this is a small problem as it stops the CPU being orientated into the board correctly.

 

Both CPUs are orientated with the gold triangle to the bottom left, as you can see the tabs are on the other sides for the 771 CPUs.

 

So how do we get round this?

Well if you were wondering where the razor blade (not the laptop mind you) came into this thing it's now, we need to remove the two plastic tabs from the LGA775 socket so our Xeon fits as it doesn't have the indents in the correct place. If you have a spare/broken/crappy LGA775 board you can practice on that first before you take a blade to your nice P45 board.

 

The process isn't massively difficult, it requires a decent amount of pressure to get through the plastics and just do a sawing motion avoiding contact with the pins on the motherboard.

 

When the process is complete the tabs should be cleanly off and the LGA771 CPU should be able to drop into the socket without any force.

 

Now what?

Now your CPU is installed to your board and you have the cooler on etc, boot it up- hopefully it should boot 1st or 2nd time (might need a CMOS reset), if it doesn't boot try cleaning the CPU and blowing on the socket and trying again, failing that try your old 775 CPU, if that doesn't work inspect for socket damage.. Now on most boards you might get a message a bit like "unrecognised CPU detected please install the BIOS to get full functionality".

 

Now- your PC will work properly without doing this however you will lose SSE4.1 instructions and you'll get this annoying message on boot, so you will probably want to "add" support to your motherboard's BIOS for your CPU.

 

To do this you need to identify whether your board is AMI or AwardBIOS. You can tell via the splash screen for your board that gives you the message. Your board should look like one of the two screenshots above. The top is Award and the bottom is AMI.

 

Instructions to add support - includes info for OEM BIOS

At some point I may write my own instructions for this, but again delidded.com has a very good guide found here. If this does not work post below and I will attempt to assist you.

At some point I may write my own instructions for this, but again delidded.com has a very good guide found here. If this does not work post below and I will attempt to assist you.

 

Video Guide by @Jumper118

https://www.youtube.com/watch?v=xCTWMMhA0ro

 

FAQ

Q - Why would I do this?

A - LGA771 CPUs are often much cheaper than their LGA775 equivalents, and Xeons are better binned so they usually overclock better.

 

Q - Can I overclock the Xeon?

A - Yes, it supports overclocking the same way regular 775 CPUs does, you can find my LGA775 overclocking guide in my signature.

 

Q - Can I/do I need to use ECC RAM?

A - No. The LGA775 memory controller is not on the chip itself so it's individual to your board, so use regular DDR2 RAM.

 

Q - Is it possible to buy pre-modded CPUs?

A - Yes but you'll usually pay more, it's very easy to do it yourself.

Q - I broke my board and/or CPU! Can I sue you?

A - No.

[Aniallation]

Although it wasn't worded as well, it's been posted before http://linustechtips.com/main/topic/363422-how-to-using-a-lga-771-xeon-in-a-lga-775-motherboard-aka-771-mod/

[Syntaxvgm]

Although it wasn't worded as well, it's been posted before http://linustechtips.com/main/topic/363422-how-to-using-a-lga-771-xeon-in-a-lga-775-motherboard-aka-771-mod/

there's not such thing as a repost when it comes to guides my friend.

 

Thanks for the tutorial. 

[harrynowl]

Although it wasn't worded as well, it's been posted before http://linustechtips.com/main/topic/363422-how-to-using-a-lga-771-xeon-in-a-lga-775-motherboard-aka-771-mod/

Welp, I hadn't seen that one. I've been planning to write this for a while and I got ninjad

 

Thanks for the tutorial. 

Thanks

[Jumper118]

Welp, I hadn't seen that one. I've been planning to write this for a while and I got ninjad

 

Thanks

lol. got beaten to it by 4 days . your guide has more pics though so it is better. i really should do this to my board. 

[AMICLG]

Nice tutorial, brings me back to the LGA 775 days. It might be easier if you heat up the blade of a x-acto knife to cut off the notches. I thought about doing this years ago but never got around to it. I've have a P5N-D laying around that should work, other than the horrible voltage droop and not liking being run over 1700Mhz on the FSB with a dual and 1500Mhz with a quad, it wasn't a bad board.

[Gikero]

I have a EVGA 790i SLI ruuning a Xeon E5472 @ 3Ghz and 8GBs of DDR3 Crucial Ballistix 1600Mhz RAM and loving it.
I have another Asus Maximus Formula with a Xeon X3363 @ 2.8Ghz and 8GBs of DDR2 Samsung 800Mhz RAM. Both are stable and fast. Just wish I could do 16Bs of DDR3 in each. I have 2-3 more LGA 775 mobos that I want to do this with and sell as cheap gaming systems.



One the the guides on this site helped me and that was the reason I became a member of Linustechtips.com. ^__^

[Jumper118]

I have a EVGA 790i SLI ruuning a Xeon E5472 @ 3Ghz and 8GBs of DDR3 Crucial Ballistix 1600Mhz RAM and loving it.

I have another Asus Maximus Formula with a Xeon X3363 @ 2.8Ghz and 8GBs of DDR2 Samsung 800Mhz RAM. Both are stable and fast. Just wish I could do 16Bs of DDR3 in each. I have 2-3 more LGA 775 mobos that I want to do this with and sell as cheap gaming systems.

One the the guides on this site helped me and that was the reason I became a member of Linustechtips.com. ^__^

i would hope they are both stable at stock speeds!

[Gikero]

i would hope they are both stable at stock speeds!

Ha ha! Ya, I want to try overclocking. I specified stable because technically, I'm running a unsupported processor on those motherboards.

 

[Jumper118]

Ha ha! Ya, I want to try overclocking. I specified stable because technically, I'm running a unsupported processor on those motherboards.

 

well here is the best guide on the internet for 775 overclocking: http://linustechtips.com/main/topic/232325-lga775-core2duo-core2quad-overclocking-guide/ 

[ungreedy]

sweet guide ,I might have to get one of those xeons to tinker with.

 

what chips should I be looking to get and what motherboards?

 

would the x5460 work with this mod?

[Dabombinable]

sweet guide ,I might have to get one of those xeons to tinker with.

 

what chips should I be looking to get and what motherboards?

 

would the x5460 work with this mod?

Well the lower clocked X5450 does so yes. Just make sure that your motherboard supports the high end Q9***/QX9*** CPU's first.

[ungreedy]

Well the lower clocked X5450 does so yes. Just make sure that your motherboard supports the high end Q9***/QX9*** CPU's first.

sweet I will have to keep a look out for cheap boards on craigslist ,the cpus on ebay are dirt cheap.

 

thanks

[Dabombinable]

sweet I will have to keep a look out for cheap boards on craigslist ,the cpus on ebay are dirt cheap.

 

thanks

A P5Q board from Asus would be perfect. Also, if you see an Xeon E5450 and its cheaper than an X5460 (which it should be) buy it instead. Its a lower TDP version of the X5450.

[ungreedy]

A P5Q board from Asus would be perfect. Also, if you see an Xeon E5450 and its cheaper than an X5460 (which it should be) buy it instead. Its a lower TDP version of the X5450.

know of any m-itx boards that would work?

[Dabombinable]

know of any m-itx boards that would work?

I've never actually looked at buying one, but I can say right now that they are extremely rare and unless you want to buy 2x 4GB sticks of DDR2 @ over $100 per stick, then your limited to 4GB RAM.

[arnavvr]

There is a Zotac board, and also the Gigabyte EP45-UD3R is a also a good board.

[harrynowl]

know of any m-itx boards that would work?

Zotac had an ITX board but given the fact these chips give the FX series a run for their money in the power consumption department, I'd steer clear of that kind of board

[ProKoN]

can you please verify this works on a x48 rampage formula before i cutter up the socket?

 

i dont think its gonna work.....effin x48

 

An alternative to modding the socket is to file down the cpu's pcb with a round file. im gonna give that a go on the x5260.

[Jumper118]

can you please verify this works on a x48 rampage formula before i cutter up the socket?

 

i dont think its gonna work.....effin x48

 

An alternative to modding the socket is to file down the cpu's pcb with a round file. im gonna give that a go on the x5260.

lol asus and x48 is the worst possible combo for this mod  

[Rheinwasser]

i wont do that myself, but thats sick!

to bad these kinds of mods arent possible anymore these days.

[arnavvr]

@harrynowl Is an NForce 610i compatible?

[Dabombinable]

@harrynowl Is an NForce 610i compatible?

If I remember correctly, the chipset doesn't work that well with quad cores.

[arnavvr]

If I remember correctly, the chipset doesn't work that well with quad cores.

 

It says 1066Mhz Max FSB. 

[Dabombinable]

It says 1066Mhz Max FSB. 

Well then barely. My Xeon X5450 at 3.6GHz is running the FSB at 1600MHz (400MHz x 4).