32GB EUDIMMs are now widely available in retail channels (last year and in prior years they were mostly only available in commercial channels). You can buy them on Amazon.

64GB and 128GB EUDIMMs are only available in commercial channels insofar as I can tell. And expensive as hell... and have to be run at 2133 due to the line load. Not really the best fit for a threadripper, honestly. If you need that sort of capacity you would be buying an EPYC and not a TR.

-Matt

There are actually not very many workloads that will blow out the available ram bandwidth on a Zen 2 threadripper. The huge CPU caches make up for a lot. The 3990X will have 256MB of L3 cache and since there is only one NUMA zone it can distribute the memory load evenly across all 8 slots.

Given the performance we see with its smaller brother (the AM4 consumer 3950X with 16-cores and 64MB of L3), it is clearly not going to have any problems for most workloads.

-Matt

Ram capacity for the retail AMD chips like the 3900X or 3950X (really any Zen 2 AM4 chip), and both Zen+ and Zen 2 threadripper chips, is limited by the fact that there is only support for unbuffered DIMMs.

People trying to compare Xeons against TRs based on wanting to stuff a terrabyte or more of ram wouldn't be buying a TR for that, they would be buying EPYCs, so its a stupid comparison. Its also stupid because Intel charges thousands of dollars more for Xeons with large physical address spaces (even with recent price cuts, Intel gouges buyers just for wanting more addressable ram even if they don't need the cores).

I have personally stuffed 128GB into a 3900X (AM4 socket) using 4 x 32GB ECC UDIMMs, and 256GB into a 2990WX (threadripper socket) using 8x of the same type of memory. I can run the memory at up to around 2666.

Insofar as I know, one can use 64GB DIMMs in both situations (256GB on AM4 and 512GB on TR), and I think 128GB DIMMs can be used on the TR. But since they are unbuffered, they would have to at low frequencies (1066 MHz for a 2133 MHz data rate). But the biggest DIMMs I personally own are 32GB each so I can't test higher capacities.

AM4 and TR Motherboard vendors do not generally validate for high-capacity memory, which is why they list lower capacities, but I they all support high-capacity memory just fine.

Very few people need that much memory even on a threadripper. We need it for bulk compiles... around 2GB per cpu thread, so we need around 128GB of ram with a 32-core/64-thread threadripper and 256GB of ram with a 64-core/128-thread threadripper (the 3990X releases on February 7th). Most other (likely) workloads do not need that amount of memory though, particularly when one can get NVMe storage devices with 5GByte/sec bandwidths.

The EPYC chips support 2TB per cpu socket (4TB total for dual-socket EPYCs), using registered DIMMs.

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The bigger deal with the threadrippers is the massive PCIe bandwidth. Not only do you get 128 PCIe lanes (actually more when you include the chipset), but the Zen 2 I/O hub built into the cpu chip has over 400 GBytes/sec of peer-to-peer bandwidth. Intel chips clock in at more around 100 GBytes/sec (or less).

DRAM bandwidth is roughly the same for both vendors, but AMD cleans Intel's clock out on peer-to-peer PCIe bandwidth and this is quickly going to become important in the commercial space.

-Matt

Maybe. We've heard the same phrases for Josephson junctions, magnetic bubbles, insert your favorite once-nascent technology here. There is still a big distance between demonstration and practicality.

It doesn't matter, really. Anything with content. So e.g. youtube, google news, a newspaper or two... stuff like that. Nothing fancy.

-Matt

The 'laptop crap' is a much bigger market than desktop APU. That said, I'm sure AMD will release a 4-series APU this year some time.

AMD is constrained by TSMC's wafer production volumes. AMD couldn't release all the chips at the same time even if they wanted to, TSMC just doesn't have the capacity to handle the rush.

Remember how long it took for the 3800X and 3900X to settle down to their MSRPs? It took at least 4 months, even longer. And the 3950X is only just now becoming widely available at +$40 over its MSRP.

AMD has to wait a few months for current demand spikes to ease before they can release an APU, so look for summer. TSMC is expanding its capacity and AMD will be able to take a chunk of Apple's TSMC capacity at 7nm as Apple moves to 5nm, but that's the basic constraint.

-Matt

Web clients and servers negotiate the format. Most CDNs can distribute video in numerous formats and resolutions (some even translate on the fly so they don't have to store them). Anything with hardware video acceleration in the last 10 years is likely to be supported.

-Matt

I'm sure many people will be replacing their older TR systems with newer TRX40 systems. I'm not sure why you believe people wouldn't. The TR3 chips are considerably more powerful than the TR2 chips core-for-core, older TR systems have value on the used market, and not everyone with TR2 systems are running the highest-end TR2 chips.

Someone with a 2970WX or 2990WX system probably wouldn't be upgrading (except possibly to a 3990X), but I would say that many people with a 1900X, 1950X, 2920X, or 2950X will definitely be in the market.

If these people don't upgrade to TR3, they will probably opt for upgrading to an AM4 based 3950X instead (which is a much cheaper motherboard + cpu combination than TR2/3).

-Matt