Invisible wrote:

I understand perfectly this problems.

> Another possibility is to run the main renderer on the CPU, adding rays 
> to queues, and sending any "sufficiently large" queues to the GPU for 
> processing. I don't know if bandwidth limitations between the two would 
> make this viable...


Exactly, that is why I asked: "Are absolutely sure there isn't a case 
where a GPU can help? maybe in the middle of a rendering/parsing?".

As for the bandwidth and memory concerns, from here: 
http://forums.amd.com/devforum/messageview.cfm?catid=328&threadid=95060&enterthread=y

Q: What are AMD's stream computing product features?

A: AMD's FireStreamtm 9170, our latest generation stream computing GPU, 
features:
* 320 stream cores (compute units or ALUs)
* 2GB on-board GDDR3 memory
* Double precision floating point support
* PCIe 2.0 x16 interface
View AMD FireStream 9170 specifications here: 
http://ati.amd.com/products/streamprocessor/specs.html

Memory Concern:
--------------
  Maybe would be a good idea to leave the processed data on the video 
card  local memory until is needed in Main Memory.



Bandwidth Concern:
-----------------
- M4A78 PLUS MoBo 
(http://usa.asus.com/products.aspx?l1=3&l2=149&l3=758&l4=0&model=2889&modelmenu=1):
# It features dual-channel DDR2 1066 memory support and accelerates data 



(http://www.amd.com/us/products/desktop/processors/phenom-ii/Pages/phenom-ii-key-architectural-features.aspx)
# One 16-bit link at up to 4000MT/s

HyperTransport Generation 3.0 mode
# Up to 37GB/s total delivered processor-to-system bandwidth 
(HyperTransport bus + memory bus)


PCIe Card Electromechanical 2.0 Specification 
(http://www.pcisig.com/specifications/pciexpress/base2)
# Signaling

PCI Express Base 2.0 specification doubles the interconnect bit rate 
from 2.5 GT/s to 5 GT/s in a seamless and compatible manner. The 
performance boost to 5 GT/s is by far the most important feature of the 
PCI Express 2.0 specifications. It effectively increases the aggregate 
bandwidth of a 16-lane link to approximately 16 GB/s.

- Video Card: MD FireStream 9170 (specs above)


----------------- ************** ----------------


As you can see, maybe bandwidth it isn't much of an issue since The 
transfer between the PCIe video card and the Main memory can me made at 
5 GT/s. Is this still insufficient for POV-Ray peak performance?

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