New PC dedicated to Mersenne Prime Search

[Taiy]

Hi Everybody,

First of all: I am totally noob and English is not my mother tongue :)

I started this whole mersenne prime search in 2009, when I studied matemathics on a higher level in secondary school but after a few weeks my PC broke down because of other reasons, and I finished searching for primes until today.

I decided that I would like to build a PC just to search for mersenne primes.

Can you recommend me some hardwares? Motherboard? CPU? RAM? What should you buy?

Thank you for instance
Gergő

[VictordeHolland]

- Buy a good power supply from a decent brand with good rating (80+ gold for instance)
- If you're only going to use the PC for LL-testing, than you don't need an expensive motherboard or CPU. Something like a quad-core i5 with DDR4-2400 memory will give you great bang-for-buck.

Some more advice in this thread:
http://mersenneforum.org/showthread.php?t=20795

Make sure to calculate your electricity costs (per year for instance), so you don't get unpleasant surprises when you get the energy bill.

[GP2]

A lot of graphics cards were bought for cryptocurrency mining, but I think that will soon reach the point where it's no longer practical. Either because dedicated hardware like ASICs is the only practical option, or because of a switch to different verification methods.

So maybe a bunch of used GPUs will go on sale in 2018 at attractive prices... ?

[Gordon]

Originally Posted by GP2

A lot of graphics cards were bought for cryptocurrency mining, but I think that will soon reach the point where it's no longer practical. Either because dedicated hardware like ASICs is the only practical option, or because of a switch to different verification methods.

So maybe a bunch of used GPUs will go on sale in 2018 at attractive prices... ?

On a slight side-track, I'd love an ASIC that runs mfaktc.....

[Madpoo]

Originally Posted by Gordon

On a slight side-track, I'd love an ASIC that runs mfaktc.....

I imagine it'd be something along the lines of an ASIC that did ridiculously fast FMA and had a lot of RAM caching or something. No idea of the complexity of that though and I have every reason to believe it'd probably still be more cost effective to get a CPU or GPU that already has that capability. But I could be wrong.

The ASICs for mining have a profit motive so people can and do pump a lot of research and fab into it. For anything else you'd have to rely on some really dedicated people with the right knowledge and a lot of free time.

On the other hand, the new CPUs that have FPGA capabilities might be useful. I haven't read that much about how versatile those FPGAs are but if people developed some cool libraries of functions for them, we might come across something that helps speed things up.

[Batalov]

Originally Posted by Madpoo

On the other hand, the new CPUs that have FPGA capabilities might be useful. I haven't read that much about how versatile those FPGAs are but if people developed some cool libraries of functions for them, we might come across something that helps speed things up.

FPGAs could definitely be used.

A substantially similar math problem (genome alignments) is not only been run as a PoC but is successfully commercialized. While many genome centers still run conventional CPU alignments and get the results in 8-12 hours for a typical genome on a 32-core node (typical demand is tens of thousands genomes per year at a large center, so they don't spread one genome over many nodes), the FPGA solution runs in 45 minutes on a special node. These are now available at AWS, too!

Usually, the algorithmic entry threshold is having a team of Verilog experts. This is far more involved than CUDA or OpenCL coding.

[mackerel]

Originally Posted by Taiy

I decided that I would like to build a PC just to search for mersenne primes.

Can you recommend me some hardwares? Motherboard? CPU? RAM? What should you buy?

I'm not the most familiar with Prime95 but do a lot of other forms of prime numbers mostly using LLR. With that said, you basically want to get a nice CPU, and balance it with the right speed ram. The motherboard will be supporting that. Here it comes down to budget, and how long you might keep it.

Some ideas: on the higher end, i7-7800X - 6 cores, support for quad channel ram, and AVX-512. The last part might offer a performance increase once software has been updated to support it. The CPU isn't too expensive, but the motherboards will cost more than mainstream consumer level, and you'll need 4 sticks of ram, preferably higher speed around 3000 mark. A popular budget motherboard for this is the Asus X299 TUF mark 2.

For a more mainstream idea, the i3-8100 or i3-8350k are interesting. These are 4 core CPUs, the latter supporting overclocking. You'll probably need to get a Z370 chipset motherboard to enable higher speed ram, so that it wont limit. Again, aim for ram speeds around 3000 mark, but this only needs two sticks for dual channel.

For overall work throughput, you'd have to work out if it is more efficient to run multiple simpler systems, or fewer faster ones. If only building one system, it may depend more on your budget.

Originally Posted by GP2

A lot of graphics cards were bought for cryptocurrency mining, but I think that will soon reach the point where it's no longer practical. Either because dedicated hardware like ASICs is the only practical option, or because of a switch to different verification methods.

So maybe a bunch of used GPUs will go on sale in 2018 at attractive prices... ?

Don't think anyone really knows what's going to happen. Even if some more popular ones switch from proof of work, to proof of stake, other minor coins could come up and take their place so it might be a never ending cycle. Some coins have been designed to be ASIC resistant thus GPUs may remain relevant for longer in this use case.

Originally Posted by Gordon

On a slight side-track, I'd love an ASIC that runs mfaktc.....

I've kinda wondered, what is it about the implementation that limits us to "only" 64-bit/80-bit operations? Wouldn't it be lovely to have orders of magnitude bigger registers to work with? Say kilobit? I don't know how multiplication functions are actually handled in a modern CPU, but if I were to do it from scratch I'd probably brute force a parallel long multiplication to minimise latency, with a quick sum at the end. The cost being circuit quantity (assuming integer math for now, assume principles could be expanded for floating point).

[ATH]

Originally Posted by Taiy

I decided that I would like to build a PC just to search for mersenne primes.

Can you recommend me some hardwares? Motherboard? CPU? RAM? What should you buy?

It depends on what is your budget and what is your goal? Do you want the fastest performance per dollar spent on hardware, or the fastest performance per watt of power it uses? or do you want a super fast computer that can finish the tests very fast but less efficiently?
The 2 first options might be very similar in hardware, but the 3rd option would be a totally different setup.

Do you only want to use CPU or do you want a graphic card for either trial factoring or for doing more LL tests on?

[M344587487]

Originally Posted by GP2

A lot of graphics cards were bought for cryptocurrency mining, but I think that will soon reach the point where it's no longer practical. Either because dedicated hardware like ASICs is the only practical option, or because of a switch to different verification methods.

So maybe a bunch of used GPUs will go on sale in 2018 at attractive prices... ?

I don't think GPU mining is going away anytime soon, even if the likes of Ethereum switch to PoS. At best GPUs may go back to around their MSRP if mining dies down, but I think we're out of luck when looking for cheap compute. The problem is that the cards good for mining are also the ones good for prime hunting, it would take more than mining dying down to ease demand on them. The card prices that will benefit most from a mining lull are the ones that are only profitable at the peak of mining, aka the mid-range GPUs with low amounts of RAM. Gamers are the most likely to benefit from a 2018 mining dip.

[ET_]

Originally Posted by mackerel

Some ideas: on the higher end, i7-7800X - 6 cores, support for quad channel ram, and AVX-512. The last part might offer a performance increase once software has been updated to support it. The CPU isn't too expensive, but the motherboards will cost more than mainstream consumer level, and you'll need 4 sticks of ram, preferably higher speed around 3000 mark. A popular budget motherboard for this is the Asus X299 TUF mark 2.

Any hints about the brand/producer of the RAM? Is G-Skill/Ripjaws still the preferred ?

[kladner]

Go for dual-rank DIMMs. There is a distinct performance boost. Kingston HyperX is serving me well.

Unfortunately, I see that fewer of their spec sheets state Rank than I remember. The only dual set I found is 16GB parts.