Oban

Winchester CGPU

Part Number	X888839 X888841
Introduced	Late 2014
Designed By	ATi IBM Microsoft NEC (eDRAM)
Type	XCGPU
Used In	Winchester
Clock Speed	3.2GHz (CPU) 500MHz (GPU)
Cache	L1: 32KB/32KB (CPU) L2: 1MB (CPU)
Memory	10MB eDRAM (GPU)
Instruction Set	PowerPC RISC (CPU)
Cores	3 (CPU)
Threads	6 (CPU)
Process	Unknown
Package	Flip-chip BGA899
Predecessor	Valhalla

Oban is the final XCGPU and is used on the Winchester motherboard. The name of the chip is not known. It is the successor to Valhalla. The chip combines the eDRAM into the CGPU die and thus the Integrated Heat Spreader is no longer used. Little else is known about this chip.

Specifications

CPU

• 3 two-way SMD-capable RISC cores clocked at 3.2GHz
• SIMD: Two VMX128 units
• 32KB L1 data cache
• 32KB L1 instruction cache
• 1MB L2 cache at 1.6 GHz with a 256-bit bus
• 21.6GB/s FSB
• 768 bits of IBM eFUSE One-Time-Program memory for fusesets
• One-Time-Programmable ROM and 64KB SRAM for the 1BL and Config Ring
• Big-endian architecture
• A03 stepping

GPU

• 500Mhz clock speed
• 48 floating-point vector processors divided into 3 dynamically scheduled SIMD groups (16 each)
• Unified shader architecture
• 16 texture addressing units
• 16 texture filtering units
• 8 pixel rendering pipelines
• Direct access to CPU L2 cache
• A03 stepping

eDRAM

• 10MB 256GB/s eDRAM
• Contains logic for:
  • 4-sample anti-aliasing
  • Alpha compositing
  • Color
  • Z/stencil buffering
• A03 stepping

Details

• Part Numbers:
  • X888839
  • X888841