GENERAL New Xbox 360 CPU eFuses and Dashboard questions.

[BabaOeeRock]

Perhaps someone can point me in the right direction. I understand most people don't like spoon-feeding information but, I can't seem seem to find an answer on thru google search and I am a noob.

It is my understanding that dashboard updates burn so called "efuses" inside the CPU not the GPU. I was wondering if one were to install a brand new CPU on the motherboard what exactly would happen. Is the dashboard info stored within the CPU? If so, I am guessing that date of manufacturing would be important. anybody have any idea?

 

[BL4K3Y]

Why do you need to install a new CPU?

The eFUSEs are stored in the CPU, but you also need the matching NAND because it is encrypted with the console's CPU key.

 

[BabaOeeRock]

Why do you need to install a new CPU?

The eFUSEs are stored in the CPU, but you need to remember that you also need the matching NAND because it is encrypted with the console's CPU key.

I don't need a new CPU. I am asking to learn how it works. Since you can't downgrade dashboards due to blown eFuses which are located within the CPU, I was wondering what would happen if you bought a new CPU (which has no blown eFuses) and installed it on the motherboard.

So, where exactly is the NAND located then?

 

[gavin_darkglide]

the nand is located on the motherboard. Why would you want to downgrade the system? if it is on the latest dashboard, you can downgrade to 15574 or newer, as what is important is the cb version used on the console. To do this you will need to RGH the console to get the CPU key, then build a new retail nand. I personally would just install the rgh and use Freeboot, which will allow homebrew. Also, some of the efuses are blown in the factory.(Cpu key, console type(Retail, or devkit.))

 

[Krafter]

I think he's just asking a general question trying to learn something.

A CPU and a NAND or flash memory go hand in hand. Not only are the eFuses burnt in the CPU but there is an encryption key as well. The key is used to encrypt the contents of the NAND. So if the CPU and NAND are not paired then the Xbox won't boot.

To answer your question, yes it is possible to change the CPU of a lower eFuse of the same type and put it on a console but only if you have its matching NAND dump.

 

[BabaOeeRock]

I think he's just asking a general question trying to learn something.

A CPU and a NAND or flash memory go hand in hand. Not only are the eFuses burnt in the CPU but there is an encryption key as well. The key is used to encrypt the contents of the NAND. So if the CPU and NAND are not paired then the Xbox won't boot.

To answer your question, yes it is possible to change the CPU of a lower eFuse of the same type and put it on a console but only if you have its matching NAND dump.

Thank you Krafter for your explanation. So, the NAND is stored in a chip on the motherboard. What chip, exactly?

I am guessing you cannot buy and replace these chips, correct?

So, is there anyway of installing a brand new CPU and make it work with with you current NAND?

What I am getting is, since a new CPU (that has no blown eFuses) is installed, can the NAND be flashed to an original or previous NAND? Example, for the purposes of Jtagging

 

[gavin_darkglide]

the only way to get a cpu with no blown efuses would be to get it off the assembly line from microsoft. Microsoft will never sell a cpu like this. there are efuses blown at the factory, as the console type and cpu_key are stored in the efuses. the efuses that you need to worry about are the CB LDV(Fuseset 02) and the Update LDV(Fusesets 7 and 8). As for the jtag hack, if the console has been updated past 7371 it will not work, but there are other options(RGH,R-Jtag) that will accomplish the same thing.

 

[BabaOeeRock]

the efuses that you need to worry about are the CB LDV(Fuseset 02) and the Update LDV(Fusesets 7 and 8)

So, if I understand correctly, these are the eFuses that are blown when you update the dash over 7371. So, would these eFuses also be blown in an off the assembly CPU with a manufacturing date after June 2009 or whenever it is that Microsoft released the Jtag patch?

 

[gavin_darkglide]

most likely. If all you are trying to get the homebrew hack going, I should first ask what console are you using, and what dashboard are you on. I only ask, because most 360's(Non Xenon) can run homebrew via RGH/R-Jtag, so the dashboard/burned fuses dont really matter anymore. While the jtag hack was the cheaper option, there are still ways to achieve the same thing.

 

[BabaOeeRock]

most likely. If all you are trying to get the homebrew hack going, I should first ask what console are you using, and what dashboard are you on. I only ask, because most 360's(Non Xenon) can run homebrew via RGH/R-Jtag, so the dashboard/burned fuses dont really matter anymore. While the jtag hack was the cheaper option, there are still ways to achieve the same thing.

No, I'm not trying to get a JTAG done. I already have one of these units. What I am doing is trying to learn how to do mods myself. I dabble just a bit.

So, lets just say that I was able to get a CPU manufactured in 2008. Theoretically, could I install it on a motherboard and somehow flash the NAND to a previous version?

 

[gavin_darkglide]

Yes, as long as you have the keyvault/original nand dump that goes with that cpu. But this is a lot of work, and would require some expensive tools to install the new cpu, when RGH/R-Jtag will do the same thing. While Jtag is the fastest booting homebrew hack for the xbox 360, is it really worth all of the trouble of replacing the cpu, when the tool to do so properly will cost over 1000$. most people who just dabble, cannot afford that. If you want to mess with the jtag hack, the best bet would be to install r-jtag, which requires installing jtag wiring, so you can learn how to install a glitch chip, and jtag in one setup. as it is, you can downgrade to any dashboard using the same CB version(Determined by fuseset 2 in xell). so if running 16747 you can downgrade to >=15574, as this is when the latest CB version was released. This requires having the CPU key, and creating that version nand stock image with the consoles original Key Vault. As long as all the LDV's in the nand match xell, then the console will boot retail, and have been downgraded. Since you cant change the CB version to an older version, you cannot downgrade to a jtagable dash. If you are running an RGH/Jtag, you can downgrade to any freeboot image, all the way back to the original dash. there is some really good information on how all of this works at free60.org

http://free60.org/Reset_Glitch_Hack

[URL="http://free60.org/SMC_Hack"]http://free60.org/SMC_Hack

http://free60.org/Fusesets

http://free60.org/Boot_Process
[/URL]

 

[BabaOeeRock]

Ok. So, let me see if i understand correctly. If I have a system with an R-JTAG, RGH or JTAG, using freeboot I can flash the NAND all the way back to the first ever dash, as long as I have the original stock image of that NAND?

 

[gavin_darkglide]

It would be a freeboot image, but yes, essentially you could, why would you want to though? You wouldnt even need the original nand image for the version you want to run, as you can create a freeboot image for any version that xebuild supports with j-runner. As far as going back to the very first dash, I dont know if that is possible, as I dont think xebuild supports the original dash.

 

[BabaOeeRock]

It would be a freeboot image, but yes, essentially you could, why would you want to though? You wouldnt even need the original nand image for the version you want to run, as you can create a freeboot image for any version that xebuild supports with j-runner. As far as going back to the very first dash, I dont know if that is possible, as I dont think xebuild supports the original dash.

Perhaps you can point me to a tutorial on using xebuild, j-runner and freeboot as I am not familiar with these tools.


So, just to make sure, Freeboot will flash the xbox NAND to a previous dash?

So, theoretically, If I have and R-JTAG system, I can downgrade my dash using freeboot to say... something like 7371 or below, remove the R-JTAG and just install a regular JTAG?

 

[gavin_darkglide]

Freeboot is an xbox dashboard with the security checks patched out. So essentially, it allows you to run homebrew. Since it patches out security checks, it will allow you to boot any kernel, which is saved in the nand. J-runner is the ultimate jtag/rgh tool. It creates nand images, using xebuild, it also will flash nands, using a Nand-X, Jr-Programmer, or Demon. It really is the ultimate software for a modified Xbox 360. http://team-xecuter.com/forums/showthread.php?t=82434. Any downgraded dashboard you build will need some sort of glitch device(CoolRunner, R-Jtag) to boot the custom dash you build. also you will need the CPU key, to create this new freeboot image. This is all included in the j-runner pdf, that comes with it.

 

[Martin C]

Perhaps you can point me to a tutorial on using xebuild, j-runner and freeboot as I am not familiar with these tools.


So, just to make sure, Freeboot will flash the xbox NAND to a previous dash?

So, theoretically, If I have and R-JTAG system, I can downgrade my dash using freeboot to say... something like 7371 or below, remove the R-JTAG and just install a regular JTAG?

No.

I have a sticky post on LDV and efuses (in my sig). I suggest you read it.

 

[jdoe91011]

No.

I have a sticky post on LDV and efuses (in my sig). I suggest you read it.

OP, read that sticky. That's where I learned about this topic and it's a lifesaver, it should be required reading before you join the forums.

 

[BabaOeeRock]

OP, read that sticky. That's where I learned about this topic and it's a lifesaver, it should be required reading before you join the forums.

Yes. I will definitely read that sticky. I also found two great videos, both very long explaining how to do exactly what I was asking. How to replace the CPU and then flash to a JTAGable dash. One of the videos is from one of the "big guys" who advertise their modding service here on the TX forum.

Thanks for all the help guys!