GPU Retrofit

Note  This page is intended for advanced technicians only. If you do not have advanced component and BGA rework skills, you will not be able to complete the process successfully.

Some GPUs can be retrofitted onto earlier boards. This page contains instructions for what changes need to be done in order for the retrofit to work.

These instructions are not from Microsoft and were created by Octal450 via reverse engineering.

Zephyr_B/C

Both variants of the 65nm GPU, Zeus and Kronos, can be retrofitted onto a Zephyr_B/C motherboard. (Demo Video)

Instructions

GPU Table

Name	Part Number	GPU/eDRAM Lithography	GPU/eDRAM Temp Target	GPU/eDRAM Temp Critical
Zeus	X810478 X817793	65nm/90nm	71C/73C	90C/92C
Kronos	X820894	65nm/65nm	75C/77C	90C/92C

Install GPU

• Replace 90nm U4D1 with 65nm

Set VID 1.075V

• Remove 0 ohm R8B9
• Remove 0 ohm R8B10

Set FSB/PCIe/Memory Calibration

• FSB:
  • Remove 4.87K ohm R5R3
  • Install 40.2 ohm as pullup to nearby V_GPUCORE
    • You can either use a wire to the capacitor as shown, or scrape to expose V_GPUCORE voltage plane
    • 

• PCIe:
  • Remove 1.47K ohm R4R3
  • Remove 562 ohm R5D1
  • Replace 2K ohm R5D2 with 49.9 ohm
• Memory:
  • Replace 40.2 ohm R4R8 with 240 ohm
  • Replace 40.2 ohm R4T1 with 240 ohm

Tie V_GPUPCIE to V_GPUCORE

• Remove IC U5C1
• Install jumper as shown to tie V_GPUPCIE to V_GPUCORE
  • Use a 28awg or thicker gauge wire
  • Be careful not to short to any nearby components or pads
  • Strongly recommended to cover jumper with PCB mask
  • 

Modify Firmware

• Use J-Runner with Extras to dump the nand
• Change the type to Jasper 16MB, then RGH the console to get the CPU key
• Set the required XeBuild options and build the image
• Open the SMC Config Editor from the Nand menu, and update the thermal targets from the table above
• Write the nand to the console

Falcon

Both variants of the 65nm GPU, Zeus and Kronos, can be retrofitted onto a Falcon motherboard. (Demo Video)

Instructions

GPU Table

Name	Part Number	GPU/eDRAM Lithography	GPU/eDRAM Temp Target	GPU/eDRAM Temp Critical
Zeus	X810478 X817793	65nm/90nm	71C/73C	90C/92C
Kronos	X820894	65nm/65nm	75C/77C	90C/92C

Install GPU

• Replace 90nm U4D1 with 65nm

Set VID 1.075V

• Remove 0 ohm R8B9
• Remove 0 ohm R8B10

Set FSB/PCIe/Memory Calibration

• FSB:
  • Install 40.2 ohm R4R9
  • Remove 4.87K ohm R5R3
• PCIe:
  • Remove 1.47K ohm R4R3
  • Remove 562 ohm R5D1
  • Replace 2K ohm R5D2 with 49.9 ohm
• Memory:
  • Replace 40.2 ohm R4R8 with 240 ohm
  • Replace 40.2 ohm R4T1 with 240 ohm

Tie V_GPUPCIE to V_GPUCORE

• Remove 0 ohm R4C31
• Install 0 ohm R4P13
• Install 0 ohm R4P14
• Remove IC U5C1

Modify Firmware

• Use J-Runner with Extras to dump the nand
• Change the type to Jasper 16MB, then RGH the console to get the CPU key
• Set the required XeBuild options and build the image
• Open the SMC Config Editor from the Nand menu, and update the thermal targets from the table above
• Write the nand to the console

Jasper

The Kronos GPU can be retrofitted onto a Jasper motherboard. (Demo video)

Instructions

GPU Table

Name	Part Number	GPU/eDRAM Lithography	GPU/eDRAM Temp Target	GPU/eDRAM Temp Critical
Kronos	X820894	65nm/65nm	75C/77C	90C/92C

Install GPU

• Replace Zeus U4D1 with Kronos

Modify Firmware (Optional)

• This step is optional, Zeus targets 71C/73C, there is no harm by running the chip a few degrees cooler
• Use J-Runner with Extras to dump the nand
• Open the SMC Config Editor from the Nand menu, and update the thermal targets from the table above
• Write the nand to the console