buying a new computer

[Dann Corbit]

No. Calculate work accomplished per dollar. AVX makes some operations faster. So benchmark those operations. If the FLOPs/dollar is lower than it is a better investment. Maybe the flops/ core is 1/2, but you have four times the cores at half the price. The 7742 might have lower mips/ core. But number crunching throughput is going still better. A lot better. But spend your money any way you like. Smart money looks at jobs accomplished per unit time and per unit money. Drool over the per core Intel AVX power and pay through the nose for it. It's up to you.

IMO, YMMV

[Zenmastur]

No. Calculate work accomplished per dollar. AVX makes some operations faster. So benchmark those operations. If the FLOPs/dollar is lower than it is a better investment. Maybe the flops/ core is 1/2, but you have four times the cores at half the price. The 7742 might have lower mips/ core. But number crunching throughput is going still better. A lot better. But spend your money any way you like. Smart money looks at jobs accomplished per unit time and per unit money. Drool over the per core Intel AVX power and pay through the nose for it. It's up to you.

IMO, YMMV

You can trust me on this one. The only time I have ever bought Intel is when I had no other choice. I hate them almost as much as I hate Microsoft. I was just making a joke about 8280M and 9200 series because they are jokes!

Regards,

Zenmastur

[Joost Buijs]

No. Calculate work accomplished per dollar. AVX makes some operations faster. So benchmark those operations. If the FLOPs/dollar is lower than it is a better investment. Maybe the flops/ core is 1/2, but you have four times the cores at half the price. The 7742 might have lower mips/ core. But number crunching throughput is going still better. A lot better. But spend your money any way you like. Smart money looks at jobs accomplished per unit time and per unit money. Drool over the per core Intel AVX power and pay through the nose for it. It's up to you.

IMO, YMMV

You can trust me on this one. The only time I have ever bought Intel is when I had no other choice. I hate them almost as much as I hate Microsoft. I was just making a joke about 8280M and 9200 series because they are jokes!

Regards,

Zenmastur

It is never wise to hate something or somebody. Maybe you are a Microsoft and Intel hater but I'm not. In the past I used both AMD and Intel multi CPU systems and it were always the AMD systems that exhibited strange glitches and died after a couple of years. That's why I'm hesitant to buy anything from AMD, I'd rather pay somewhat more for a system that is reliable in the long run.

[Leo]

What does I/O and memory channel mean? How does it benefit chess engines?

More memory channels means that more data can travel between CPU and RAM in a given amount of time. So, for chess engines, reading information from the hash table becomes faster, for example.

Thanks. Good to know.

[Zenmastur]

No. Calculate work accomplished per dollar. AVX makes some operations faster. So benchmark those operations. If the FLOPs/dollar is lower than it is a better investment. Maybe the flops/ core is 1/2, but you have four times the cores at half the price. The 7742 might have lower mips/ core. But number crunching throughput is going still better. A lot better. But spend your money any way you like. Smart money looks at jobs accomplished per unit time and per unit money. Drool over the per core Intel AVX power and pay through the nose for it. It's up to you.

IMO, YMMV

You can trust me on this one. The only time I have ever bought Intel is when I had no other choice. I hate them almost as much as I hate Microsoft. I was just making a joke about 8280M and 9200 series because they are jokes!

Regards,

Zenmastur

It is never wise to hate something or somebody. Maybe you are a Microsoft and Intel hater but I'm not. In the past I used both AMD and Intel multi CPU systems and it were always the AMD systems that exhibited strange glitches and died after a couple of years. That's why I'm hesitant to buy anything from AMD, I'd rather pay somewhat more for a system that is reliable in the long run.

Sounds like you need a bunch of new Intel 9200 series systems!

Regards,

Zen

[Leo]

What does I/O and memory channel mean? How does it benefit chess engines?

I/O is the number of PCIe connections to the CPU. Each PCIe 3.0 "lane" connection supports 985 MB/s to... well... anything. Ethernet, GPUs, NVMe SSDs, etc. etc. On modern computers, you use x2 or x4 connections to SSDs (1.9GB/s and 3.9GB/s respectively), and x8 or x16 connections to GPUs (15.7GB/s). The M.2 slots usually use x4 connections.

Note that some CPUs support PCIe 4.0, which doubles the bandwidth. However, GPUs and SSDs which use PCIe 4.0 are extremely new and extremely expensive, so the typical CPU-builder will probably stick with PCIe 3.0 parts.

Your typical CPU (Ryzen 7 or Intel i7) will only support x16 lanes + x4 lanes to the "southbridge". The "southbridge" is all of the miscellaneous features of your motherboard lies (USB connections, SATA, maybe a legacy PCIe 2.0 or even PCI / ISA port). Some motherboards lay out the NVMe drives "behind" the southbridge, which is annoying... to say the least.

A high-end CPU like Threadripper supports x64 lanes of I/O, allowing stupifying amounts of I/O bandwidth: https://www.guru3d.com/news-story/eight ... 8-gbs.html

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DDR4 Memory channels is similar: its the number of DDR4 channels that are supported. DDR4 is clocked at different rates, but typical DDR4 is 2600 MT/s, or roughly 21GB/s. Two channels of 2600 RAM will give you 42GB/s, while Threadripper supports 4x channels, or 84GB/s.

Note that these memory channels work in parallel. Which means you only really access the full bandwidth if you use multiple threads. A single core typically only has a fraction of the memory bandwidth. This depends on details, such as NUMA architecture and microarchitectural details (in particular: cache hierarchy, load/store units, etc. etc.). Its very difficult to write a program to use all memory bandwidth available, you pretty much have to go AVX2 and very carefully lay out your memory accesses to work with the prefetchers. But more-bandwidth will (in general) help out with multi-threaded programs.

When you have 16x cores or 32x threads running on one CPU, you'll probably start to run out of memory-bandwidth.

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I/O could benefit a chess engine if you use large amounts of GPUs, SSD drives, or Network (Ethernet) connections. You could feasibly put 4x GPUs (in 8x lane configuration) + RAID0 4x NVMe SSDs + 10GbE on a Threadripper for instance, giving 4x GPUs worth of compute and maybe 10GB/s read/write speed to your Tablebase.

Memory bandwidth is far more difficult to figure out, because that's engine and data-structure specific. The easiest way to take advantgae of memory bandwidth is to increase the number of threads operating on your program.

EDIT: Actually, both I/O and Memory are very difficult to fully take advantage of. Although you have very high bandwidth available on modern machines, I/O has huge latency (and even DDR4 to an extent). So you need to learn how to write asynchronous programs, or maybe heavily multithreaded programs, to fully utilize the I/O and Memory bandwidths available today.

Thanks. Much appreciated.

[Leo]

What does I/O and memory channel mean? How does it benefit chess engines?

More memory channels means that more data can travel between CPU and RAM in a given amount of time. So, for chess engines, reading information from the hash table becomes faster, for example.

L3 caches of 1gb thanks to RLDRAM in future will be crazy.

How far into the future?

[Leo]

Reading all these posts on new high-end (CPU) computer systems made me go out and buy one . . .

What did you buy?

[ouachita]

Ryzen 9 3900X, but I've got a bunch of others available like 2699 v4, 2697 v4, et al

[Zenmastur]

Uri,

I'm curious! Did you buy a new computer yet or make a decision about what you plan to do?

I'm still waiting to see the Ryzen 3950X. There are two rumors going around about Threadripper. One says TR won't release until next year, the other says that TR low end parts will come by the end of this year, but high end will happen next year. I'm not sure I want to wait until next year for a new computer even if those CPU's come with advantages. I guess the next month or so will produce enough information to make a decision.

Regards,

Zenmastur