Back after a long hiatus. Who left all the lights on?

[Primeinator]

I hope everyone here has been doing as well as possible over the last year and that you, your family, and your friends have avoided the worst of the pandemic- both the direct assault on human life but also the myriad of economic and other problems that came its wake.

After five years of essentially zero activity on this forum or more importantly, on the number crunching front, I am finally in a position to return to contributing to the project. Perusing the forum and the main GIMPS page it seems that lot has changed in the last few years! Specifically, double-check LL tests seem like they are on their way out and PRP testing has become like the NEIPA craze.

I should be able to have my old system (i7 3820 3.6 Ghz) up and running in the next three weeks (pending needed repair of a loose fan mount vs bearing and potential need for flushing of the liquid cooling system). However, this system is certainly not as shiny as it used to be and I would like to eventually obtain a new system. With all of this being said I have a few questions:

1) With the new version 30.3 can one still select WR for work type? Is an LL test still given or does the system do a PRP test first and if that "passes" then proceeds to LL?

2) GPU seems to be the way to go. Last I remembered there was no GUI and it was all command prompt. Has this changed/become more user friendly?

3) With regards to building a new system:
My goal is to work on the infinitesimal chance of finding a new prime and my theoretical new system should be built with that in mind. My initial budget is flexible, but likely starting at ~$2,500 with ability to add additional GPUs for a "farm" if that is still the best way to go about things. Unless I am mistaken it seems like cloud computing is more expensive than building your own system? I do not do "intensive" gaming, though there are a couple of games the system needs to be able to run. I know this is a complicated question that depends upon a lot of factors.

4) Is GIMPS still in need of donations?

Thanks, all!

Edit: In the likely event my questions are asinine please feel free to refer to me the appropriate threads.

[Uncwilly]

Originally Posted by Primeinator

After five years of essentially zero activity on this forum or more importantly, on the number crunching front, I am finally in a position to return to contributing to the project.

{Insert jail /restraining order/military deployment joke here}.
Welcome back. I recognize that avatar.

With all of this being said I have a few questions:

1) With the new version 30.3 can one still select WR for work type? Is an LL test still given or does the system do a PRP test first and if that "passes" then proceeds to LL?

PRP should be used for all first time checks. If an exponent passes, then the standard LL DC assault will start (GPUs running 2 different codes, multiple CPU types and at least 2 different code packs.) The person who runs the PRP gets the credit as the discoverer.

2) GPU seems to be the way to go. Last I remembered there was no GUI and it was all command prompt. Has this changed/become more user friendly?

I can't speak to this as my built in GPU's are not suited to running said software. But, I understand that gpuOwl is much better that the older cudaLL.

3) With regards to building a new system:
My goal is to work on the infinitesimal chance of finding a new prime and my theoretical new system should be built with that in mind. My initial budget is flexible, but likely starting at ~$2,500 with ability to add additional GPUs for a "farm" if that is still the best way to go about things. Unless I am mistaken it seems like cloud computing is more expensive than building your own system? I do not do "intensive" gaming, though there are a couple of games the system needs to be able to run. I know this is a complicated question that depends upon a lot of factors.

The Radeon VII might be the hot ticket GPU wise:
https://www.mersenneforum.org/showthread.php?t=24979
How much does power cost near you and how long until you pay for the system and electricity vs your bill for the cloud match.

4) Is GIMPS still in need of donations?

The forum does. Mike has asked forumites to help cover James's server costs for Mersenne.ca Look for the tiny orange dot in the upper left of the table on the forum's main page.

[Primeinator]

Welcome back. I recognize that avatar.

Thank you! I've certainly missed it.

PRP should be used for all first time checks. ... The person who runs the PRP gets the credit as the discoverer.

Will P95 (or GPU Owl) immediately go into the LL in this instance? Or does the server provide it to another system/user?

The forum does.

Great. I can chip in. No salsa though- I'm keeping that for myself. Is there a way to give through Venmo or is it only Pay Pal?

How much does power cost near you

It is a little south of 16 cents/kWh. Not sure how that compares to other parts of the world/country.


And I assume one or two decent GPUs are still going to crush a moderately high-end CPU in terms of PRP tests completed monthly?

[Uncwilly]

Originally Posted by Primeinator

Will P95 (or GPU Owl) immediately go into the LL in this instance? Or does the server provide it to another system/user?

Like before, once a new prime candidate is found the server throws on the tin foil hat and sounds the infrasonic whistle. Then George alters the secret team of checkers and away we go. (One of the DC options that we have is the cloud. Some of those chips have their own architecture. So multiple GPU chips, x86, ARM, other Intel, and then the cloud chips.)

So, the PRP runner gets the credit. the DC's and the cert of the PRP run the helpers.
If I found the PRP, I would start an LL myself on the fastest machine I had access to with checkpoint files and residues turned on.

So far in history there are not enough PRP numbers (of all sorts) that are not prime to not believe the report. GPU Owl is dropping LL code in the latest version. If you want to run DCs with it, go ahead using the older version.

The PRP cert stage has the server do a little magic before handing out the cert job. By doing this, even if the cert gets assigned back the same person, we can trust the PRP cert (since the server does it's magic behind a curtain.) If it already isn't programmed to do so, it should also run the cert itself for any reported primes.

[Prime95]

Welcome back!

Gpuowl does not do LL -- only PRP with proofs. There are python scripts (no GUI) to automate the fetching of work and reporting results and uploading proofs. You will get WR exponents immediately. Is seems to work much better in a Linux environment, especially for AMD GPUs.

Prime95 30.3 still has a WR work type. It will do a PRP with proof. I'm not sure if you'll get assigned a DC before you get your first WR exponent.

Radeon VII is a fabulous GPU -- worth 10 Intel quad cores. Alas, with bitcoin hitting $50K, the price of a used Radeon VII has skyrocketed to the $1300 - $1500 range.

Finally, GIMPS is in good shape financially.

[kriesel]

Gpuowl 7.x does not do LL; v6.11 does. None of us should be doing LL unless we can't avoid it, except for the chosen few that might be called upon someday to LL test in parallel a secret exponent that returns "probably prime" from a PRP test.

[Primeinator]

Originally Posted by Prime95

Radeon VII is a fabulous GPU -- worth 10 Intel quad cores. Alas, with bitcoin hitting $50K, the price of a used Radeon VII has skyrocketed to the $1300 - $1500 range.

Ouch. Certainly feasible, but having multiple of them won't be possible in the next couple months. If I am unable to get one of these (it seems they have been discontinued) what is a good alternative? And I assume I can still have both the CPU and GPU churning out numbers simultaneously- what is a good CPU to buy? And will ordering (or custom building) a liquid-cooled system make much difference?

Preference: nothing that is TOO noisy or at least a system whose noise cannot be muffled with the proper tower. At some point would like to have a farm that could go in the basement but this initial system will be placed in a multipurpose room (office, reading room, play area for the pet toddler).

[Prime95]

Originally Posted by Primeinator

Preference: nothing that is TOO noisy or at least a system whose noise cannot be muffled with the proper tower. At some point would like to have a farm that could go in the basement but this initial system will be placed in a multipurpose room (office, reading room, play area for the pet toddler).

I've not kept up with the best CPU/GPU currently available. You'll need to dig around the forum for best choice in your price range.

I believe AMD Ryzen with a big L3 cache is the current best choice for CPU.

[PhilF]

Originally Posted by Prime95

Radeon VII is a fabulous GPU -- worth 10 Intel quad cores. Alas, with bitcoin hitting $50K, the price of a used Radeon VII has skyrocketed to the $1300 - $1500 range.

You are behind the times. I checked a couple of days ago and they are up to $2250 each!