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Threadripper CPUs might be price competitive with LGA1151 CPUs, but X399 motherboards start at more than the lower-end CPUs; combined you really should be compa

Threadripper CPUs might be price competitive with LGA1151 CPUs, but X399 motherboards start at more than the lower-end CPUs; combined you really should be comparing to Intel's HEDT X299 platform, which starts at about the same overall price for motherboard+CPU. And Intel's HEDT chips all have 44 lanes this year thanks to Threadripper. More importantly for deep learning (this price difference is lost in the cost of GPUs), AFAIK all X399 motherboards for Threadripper are set up as 16x/8x/16x/8x, whereas there are X299 motherboards with PCIe switches that give you 16x/16x/16x/16x with neighboring GPUs sharing bandwidth. For deep learning, each individual GPU having 16 lanes of bandwidth is more important than having to share with another GPU.

tetrazine 8y ago
I think you're right about this for many people but not all. Intel stepping up the lane counts in HEDT is definitely a good reactionary move but won't affect the budget-constrained scenarios I discussed until a few years from now because you can just buy a couple generations back. I might be wrong but I believe many X299 chips before gen 9 had 16-24 lanes? I also don't think your point about price difference insignificance is universally applicable because buying extra GPUs over time is quite common and having an extensible box with 1-2 GPUs at the start is potentially a good move. As for the PCIe switches on the X399 chipset IMO this depends on the assertion that 16x is X% better than 8x. This depends on use case and analysis of the penalty you get at 8x vary but many people would take a 10-15% penalty down the road @ 4 cards (really 5-7.5% because it only affects 2/4 cards) to save money now. I built a box with Intel because I had the capital, and most people at an industry job probably should, but if you read forum and mailing list threads many people are faced with this economic decision and are going TR - I see quite a few academics doing this. Math libraries are a good thesis topic :)

tetrazine 8y ago

I think you're right about this for many people but not all. Intel stepping up the lane counts in HEDT is definitely a good reactionary move but won't affect the budget-constrained scenarios I discussed until a few years from now because you can just buy a couple generations back. I might be wrong but I believe many X299 chips before gen 9 had 16-24 lanes? I also don't think your point about price difference insignificance is universally applicable because buying extra GPUs over time is quite common and having an extensible box with 1-2 GPUs at the start is potentially a good move. As for the PCIe switches on the X399 chipset IMO this depends on the assertion that 16x is X% better than 8x. This depends on use case and analysis of the penalty you get at 8x vary but many people would take a 10-15% penalty down the road @ 4 cards (really 5-7.5% because it only affects 2/4 cards) to save money now. I built a box with Intel because I had the capital, and most people at an industry job probably should, but if you read forum and mailing list threads many people are faced with this economic decision and are going TR - I see quite a few academics doing this. Math libraries are a good thesis topic :)