Modifying the cpu microcode, is it possible?

[Nik16]

So, I wanted to buy an HP GL380 with 2 Xeon x5650 and replace them with x5690, only to find that they still cost a lot, and in my search of how to unlock the multiplier of a cpu on a server motherboard with a standard non-oc-capable bios,

I came across a post on a forum where a user claimed that you could, in fact, modify the cpu microcode to mask it as another cpu and get more performance.

 

So, if I get this correctly, theoretically you could actually download an x5690 microcode from Intel's website and compare the x5650 microcode to it to find and replace the string identifying the cpu, then flash the microcode and you'd have an x5650 clocked to the same speed as an x5690, which would in turn get you x5690-like performance.

 

My question is: is it actually possible to do that? and, if yes, then couldn't you just find the strings that correspond to the base and boost clock in x5650 microcode and just increase them?

I'd really like someone to look into this.

[nextg3n]

4 minutes ago, Nik16 said:

So, I wanted to buy an HP GL380 with 2 Xeon x5650 and replace them with x5690, only to find that they still cost a lot, and in my search of how to unlock the multiplier of a cpu on a server motherboard with a standard non-oc-capable bios,

I came across a post on a forum where a user claimed that you could, in fact, modify the cpu microcode to mask it as another cpu and get more performance.

 

So, if I get this correctly, theoretically you could actually download an x5690 microcode from Intel's website and compare the x5650 microcode to it to find and replace the string identifying the cpu, then flash the microcode and you'd have an x5650 clocked to the same speed as an x5690, which would in turn get you x5690-like performance.

 

My question is: is it actually possible to do that? and, if yes, then couldn't you just find the strings that correspond to the base and boost clock in x5650 microcode and just increase them?

I'd really like someone to look into this.

it is possible but extremly dangerous... additionally you probably will need to do sth about the cooling... if i were you id not waste my time with something that has so much to lose and so little to gain...

[Devryd]

But if you really want to do that, it would be really interesting. Please keep us posted if you try to do that

[porina]

I haven't tried it myself but came across similar in the past. It should be noted there are more complications than "just" changing the microcode. Microcode may be updated from bios or operating system. If you have an older version in bios, the OS can replace it. I suspect this is why non-K overclocking stopped working after a while as later microcode closed that off. So you would also have to attack it at the OS to prevent this happening.

 

Basically it is an awful lot of work for not much gain. If you really want to find a way to do it, feel free, but IMO it isn't worth it.

[Nik16]

So, the actual documentation on "microcode hacking" is pretty scarce, in that it consists of these three webpages:

https://arstechnica.com/civis/viewtopic.php?f=8&t=1062705 - A user claims that another user claims that he's able to modify Intel Celeron microcodes to make them into PIIs and PIIIs and asks if it's actually possible,a lot of people say basically no

https://security.stackexchange.com/questions/29730/processor-microcode-manipulation-to-change-opcodes - Someone else probably saw that post and thought that he could get more security by obscuring the instruction set and asked if it was possible, answers from this post explain a lot about microcodes but say that modifying them is pretty much impossible

https://hackaday.com/2017/12/28/34c3-hacking-into-a-cpus-microcode/ - The Ruhr University actually took note of that and started reverse engineering AMD K8 and K10 microcode, to some degree of success

 

So, apparently no, you can't modify the cpu microcode.

 

But there are tools to modify the BIOS and apparently the BIOS is what controls if the cpu multiplier is locked or not, standing by this "evidence":

https://www.eurogamer.net/articles/digitalfoundry-2015-locked-intel-cpus-can-now-be-overclocked

https://www.overclock.net/forum/5-intel-cpus/3750-asus-unlocked-multiplier-cpu-bios-1006-a.html

 

https://www.overclock.net/forum/5-intel-cpus/128483-unlock-intel-multiplier.html - Post #9 and #10

 

Also, there are two very interesting cinebench results listed here:

 

Apparently they are using some kind of dual-socket motherboard with dual x5650 cpus clocked at 3.49 and 3.40 GHz, which is about 400MHz above even the max boost clock of the x5650 and more in line with the base clock of 3.46 GHz of the x5690,

Sooo... I don't know. If anyone knows how to do it, please tell me.

 

EDIT: I found that soemone overclocked two x5650 with SetFSB on the Dell T7500, tho only to 3.1 GHz.

https://www.overclock.net/forum/5-intel-cpus/1643221-how-overclocking-dual-xeon-dell-precision-t7500.html

[Yuri Menini]

On 11/5/2019 at 12:45 PM, Nik16 said:

So, the actual documentation on "microcode hacking" is pretty scarce, in that it consists of these three webpages:

https://arstechnica.com/civis/viewtopic.php?f=8&t=1062705 - A user claims that another user claims that he's able to modify Intel Celeron microcodes to make them into PIIs and PIIIs and asks if it's actually possible,a lot of people say basically no

https://security.stackexchange.com/questions/29730/processor-microcode-manipulation-to-change-opcodes - Someone else probably saw that post and thought that he could get more security by obscuring the instruction set and asked if it was possible, answers from this post explain a lot about microcodes but say that modifying them is pretty much impossible

https://hackaday.com/2017/12/28/34c3-hacking-into-a-cpus-microcode/ - The Ruhr University actually took note of that and started reverse engineering AMD K8 and K10 microcode, to some degree of success

 

So, apparently no, you can't modify the cpu microcode.

 

But there are tools to modify the BIOS and apparently the BIOS is what controls if the cpu multiplier is locked or not, standing by this "evidence":

https://www.eurogamer.net/articles/digitalfoundry-2015-locked-intel-cpus-can-now-be-overclocked

https://www.overclock.net/forum/5-intel-cpus/3750-asus-unlocked-multiplier-cpu-bios-1006-a.html

 

https://www.overclock.net/forum/5-intel-cpus/128483-unlock-intel-multiplier.html - Post #9 and #10

 

Also, there are two very interesting cinebench results listed here:

 

Apparently they are using some kind of dual-socket motherboard with dual x5650 cpus clocked at 3.49 and 3.40 GHz, which is about 400MHz above even the max boost clock of the x5650 and more in line with the base clock of 3.46 GHz of the x5690,

Sooo... I don't know. If anyone knows how to do it, please tell me.

 

EDIT: I found that soemone overclocked two x5650 with SetFSB on the Dell T7500, tho only to 3.1 GHz.

https://www.overclock.net/forum/5-intel-cpus/1643221-how-overclocking-dual-xeon-dell-precision-t7500.html

So buddy, I was able to modify a part of the BIOS of a motherboard that I had here, it was a G31M-VS2 that had no support for unlocking the core multiplier, but after some microcode changes and some blue screens, I was able to modify it so that I could "unlock" the multiplier, and this with a Xeon E5430.

But after all this work I found that the motherboard couldn't handle the 10m power consumption so I can only use the Xeon with 8m, although it is a frustrating experience. I really enjoyed it.

Ps: Xeon e5430 is a 771 processor.

Ps²: G31M-VS2 is a 775 motherboard.

Ps³: This computer is my guinea pig.

If you want some images I can send them later.

[Biomecanoid]

On 11/5/2019 at 4:10 PM, Nik16 said:

So, I wanted to buy an HP GL380 with 2 Xeon x5650 and replace them with x5690, only to find that they still cost a lot, and in my search of how to unlock the multiplier of a cpu on a server motherboard with a standard non-oc-capable bios,

I came across a post on a forum where a user claimed that you could, in fact, modify the cpu microcode to mask it as another cpu and get more performance.

 

So, if I get this correctly, theoretically you could actually download an x5690 microcode from Intel's website and compare the x5650 microcode to it to find and replace the string identifying the cpu, then flash the microcode and you'd have an x5650 clocked to the same speed as an x5690, which would in turn get you x5690-like performance.

 

My question is: is it actually possible to do that? and, if yes, then couldn't you just find the strings that correspond to the base and boost clock in x5650 microcode and just increase them?

I'd really like someone to look into this.

x5690 and w3690 are cheap ranging from 30 to 50 usd. I personally got a w3680 for 30 usd and overclocked it to 4ghz.

 

Here are my threads on HP Z400 and xw8400:

 

 

 

 

 

 

[lolvatveo]

the most important thing here is not how difficult it is to hack microcode, but it is secured by signed microcode. if you flash a bios with microcode which mismatched signatures, you might end up ruining the mobo

[Ebony Falcon]

On 8/4/2023 at 7:33 AM, lolvatveo said:

the most important thing here is not how difficult it is to hack microcode, but it is secured by signed microcode. if you flash a bios with microcode which mismatched signatures, you might end up ruining the mobo

2 years late bro