What will be like for GTX 295

I have a GTX 295. And I plan to use the dual cores simulaneoustly.(In fact, I plug 3 GTX 295 to do 6 tasks at once, 8 cpu cores, 24GB host memory)
What will the following cases be like?

  1. When doing memory copy from host to device, will the bandwithd be shared or the copy time will be the same as single core(GTX 285)?
  2. How many sps are in these two cores? 240 sps for each or 120sps for each?
  3. Is it possible to do memory copy between these two core, how to make it?
  4. How to do the sync between these two core?
  5. any other drawback between using one GTX 295 and two GTX 285?

And if only performance is concerned. is threre difference between Qurdo and GTX series board?

The two CUDA devices share the PCI-Express bandwidth through a switch. If only one of the two devices on the card are transferring, that device can use the full bandwidth like a single device card. If both devices transfer simultaneously, then each device only gets half the bandwidth.

Each CUDA device in a GTX 295 has 240 stream processors.

There is still no mechanism in CUDA to copy data from one GPU directly to another one. You have to copy the data from GPU #1 to the host with host thread #1, then copy from host thread #2 to GPU #2. To make this as fast as possible, you should declare pinned memory to be portable between threads. This requires calling cudaHostAlloc() with the cudaHostAllocPortable flag. (See CUDA 2.2 release notes.)

There is no synchronization between the two devices. They are treated like two completely independent cards that share a PCI-Express slot.

None that I’m aware of.

No, as long as you match the compute capability (1.3 for GTX 200 cards), clock rate, # of stream processors, and memory bandwidth, there should be no performance difference.

Thank you so much to reply my question.

It totally clears my question marks.