4 ms·
Actually, no. It only limits the available I/O bandwidth to those GPU(s), that is, data transfers from and to the CPU will be far slower. You'll notice in games
by c00lio 3y ago
Actually, no. It only limits the available I/O bandwidth to those GPU(s), that is, data transfers from and to the CPU will be far slower. You'll notice in games when the "loading next level" screen takes longer, that's usually a large geometry and texture copy to the GPU.
As an extreme example, when and where it was/is still viable, cryptocurrency mining operations use external PCIe cases with lots of slots, attached to only a few or even just one lane per case. For their purpose this was still viable, since mining uses very little I/O from/to the GPU, essentially only a small block of setup data into the GPU ("try hashing this block, vary those bytes within that range, report when result matches this pattern", a few kB) and a few bytes of results out ("found a match, varied bytes were as follows").
- phire 3y agoIn the case of multi-gpu gaming, loading might not be an issue. You are sending the exact same data to both GPUs. If the the PCIe switch and GPU drivers support multicast, then you would actually get the full 16x bandwidth to both. Which is actually a huge advantage over the most common multi-gpu setup, which is forced to statically split the 16 PCIe lanes into two independent 8x slots. Even if you were playing a game that only used one GPU, simply having the second gpu plugged in meant your total bandwidth to each gpu was limited to 8x speed. I really wish you could find x86 motherboards with PCIe switch chips... but switch chips are really expensive so nobody makes them.