In addition to the previously leaked specs for Microsoft's next generation system, the Xbox 720, yesterday VgLeaks provided a detailed look at this system's GPU capabilities. In conjunction with a detailed image of the structure of this system, we have also been granted a table that describes each of the features within the GPU for the Xbox 720.
Below, you can view the information that has been listed:
Clock rate
800 MHz
Compute
Shader cores
12
Instruction issue rate
12 SCs * 4 SIMDs * 16 threads/clock = 768 ops/clock
FLOPs
768 ops/clock * (1 mul + 1 add) * 800 MHz = 1.2 TFLOPS
Interpolation
( 768 ops/clock / 2 ops ) * 800 MHz = 307.2 Gfloat/sec
Geometry
Triangle rate
2 tri/clock * 800 MHz = 1.6 Gtri/sec
Vertex rate
2 vert/clock * 800 MHz = 1.6 Gvert/sec
Vertex/buffer fetch rate (4 bytes)
4 elements/clock * 12 SCs * 800 MHz = 38.4 Gelement/sec
Vertex/Buffer data rate from cache
38.4 Gelements/sec * 4 bytes = 153.6 GB/sec
Memory
Peak throughput from main RAM
68 GB/sec
Peak throughput from ESRAM
128 bytes/clock * 800 MHz = 102.4 GB/sec
ESRAM size
32 MB
GSM size
64 KB
LSM size
12 SCs * 64 KB = 768 KB
L2 cache size
4 x 128 KB = 512 KB (shared)
Texture
Bilinear fetch rate (4 bytes)
4 fetches/clock * 12 SCs * 800 MHz = 38.4 Gtexels/sec
Bilinear data rate from cache
38.4 Gtexels/sec * 4 bytes = 153.6 GB/sec
L1 cache size
16 KB/SC * 12 SCs = 192 KB (nonshared)
Output
Color/depth blocks
4
Pixel clear rate
1 8×8 tile/clock * 4 DBs * 800 MHz = 204.8 Gpixel/sec
Pixel hierarchical Z cull rate
1 8×8 tile/clock * 4 DBs * 800 MHz = 204.8 Gpixel/sec
Sample Z cull rate
16 /clock * 4 DBs * 800 MHz = 51.2 Gsample/sec
Pixel emit rate
4 /clock * 4 DBs * 800 MHz = 12.8 Gpixel/sec
Pixel resolve rate
4 /clock * 4 DBs * 800 MHz = 12.8 Gpixel/sec
In addition to this, information regarding virtual addressing has been detailed. It has been stated that all GPU memory accesses on the Xbox 720 uses virtual addresses. This will eliminate the problem of resource memory fragmentation in hardware, as a single source can now reside on several pages of physical memory without causing issues.
Speaking of ESRAM, it is stated that the Xbox 720 is free from the restrictions that were supplied with EDRAM on the Xbox 360. The Xbox 720 supports texturing from ESRAM, rendering to surfaces in RAM, and read back from render targets without performing a resolve. You can view additional details on the official post that VgLeaks.
For those interested, you can view a few concept photos of the Xbox 720 in the slideshow featured above this article.
Comments