Seeking comments on PC build for Mprime

[section31]

I am looking to build a new system to do first LL tests. My goal is to get the smallest exponents and process as many of them as possible as quickly as possible. I will run the Slax OS in text mode, entirely in memory. Considerations:

I do NOT need a video card, storage, or operating system. I need at least 2 USB ports on the front (not the top), along with filtered air intake and mounting for front fans. I prefer a mid-tower case that does not have a window, but I could live with one that does. I just think that's cheesey. I do not need fast ram (... or do I? This machine will only run mprime. I won't use it for anything else.) or anything more than 1 GB. The motherboard needs onboard video (to be used for text only), and network connection. The CPU cooler needs to be adequate/mid range.

I am looking to build this system for as little money as possible, but I am not looking for cheap components! For all components I am willing to pay more for quality, safety, durability, cooling, and power efficiency. I am not concerned with aesthetics or noise.

Using Newegg's PC Builder, this is what I've come up with so far:

$74.99 Corsair Carbide Series 200R Black Steel / Plastic Compact ATX Mid Tower Case

$99.99 ASRock B365 Pro4 LGA 1151 (300 Series) Intel B365 SATA 6Gb/s ATX Intel Motherboard

$349.99 Intel Core i7-8700K Coffee Lake 6-Core 3.7 GHz (4.7 GHz Turbo) LGA 1151 (300 Series) 95W BX80684I78700K Desktop Processor Intel UHD Graphics 630

$119.99 EVGA Supernova 550 GA 550W 80 PLUS Gold Fully Modular Power Supply

$19.99 G.SKILL Aegis 4GB 288-Pin DDR4 SDRAM DDR4 2133 (PC4 17000) Intel Z170 Platform / Intel X99 Platform Desktop Memory Model F4-2133C15S-4GIS

$29.30 Thermaltake Gravity i2 95W 7-Bladed 92mm 4-Pins PWM Aluminum Extrusion CPU Cooling Fan for Intel LGA 1156/1155/1150/1151 CLP0556-D

System total: $694.25

I have built a handful of PCs before, but my last real build was over fifteen years ago, and I wouldn't be surprised if that shows up in my product selection. I'm posting here because I'm fairly certain I'm still in the stage where I don't know what I don't know.

I would love for this this machine to last for at least ten years. My last real build from fifteen years ago is still running. It's an AMD Athlon XP 1800+, producing one or two ECM results per day.

[kriesel]

Turn off your old slow Athlon and save the electricity cost to buy better hardware. (Same advice I got from George Woltman about a 386, in 1996.)
Don't do LL, which historically has a 2% error rate and at best has 50% error detection with the expensive Jacobi check.
Do first time PRP with the excellent reliability GEC error detection and correction.
Any code worth running (mprime, mlucas) will probably be memory bound. Fast memory is key to good performance (but not faster spec than the cpu and motherboard can fully use). Use all the channels.
You will need an OS, but linux doesn't cost anything.
Some sort of OS, program, and data storage. Backup provisions.
For about the price you showed, you could buy a new Radeon VII and cheap used workstation system to put it in, and produce around 10x the results per day, at less power cost each, running gpuowl.
Learn about gpu computing. https://mersenneforum.org/forumdisplay.php?f=92
Also cloud computing, with cpu or gpu or both. Including for free. https://www.mersenneforum.org/showthread.php?t=24839
General reference, grown over about 2 years: https://mersenneforum.org/showthread.php?t=24607
But note, it can escalate and become addicting/expensive. https://mersenneforum.org/showthread.php?t=24979

[Prime95]

6 cores will easily saturate DDR4-3200.

Look into AMD offerings with 64MB or more of L3 cache. I'm not very AMD knowledgeable, but the large cache may well be a solution to the RAM bottleneck. Read some of the Ryzen threads to see if this is a good fit for you.

[paulunderwood]

Rather than head for high end Intel chips, aim for an AMD Radeon VII GPU. It is equivalent to 10x four-core Intel chips. The 9100F (needs GPU, socket 1151 v2) is a cheap chip from Intel. Have a sufficiently beefy PSU for the AMD GPU. And 2x 4GB RAM.

[section31]

Thanks for your suggestions everyone. I did consider getting a Radeon VII, but Newegg has been out of them for a while, Tigerdirect doesn't seem to sell them, and Amazon has them but for $1100 instead of $550. One YouTube video I watched about it said that AMD isn't making them anymore. The next best card on the benchmark page for less than $1000 is the Tesla K80. Its numbers are about 1/3 of the Radeon VII, but it's not 1/3 the price. So I'm considering building a minimal PC around the CPU with the best performance on the benchmarks page, with the possibility/probability of adding more to it later. I can see, though, how it might be better just to wait until the Radeon VII comes back in stock.

The cloud computing one is interesting. I'm doing a DD on a GPU there now. A lot faster than the Quadro K600 I was running it on before, but that's not a surprise.

[Runtime Error]

Hi section31,

I'm actually running Prime95 on a machine with an i7-8700k processor and DDR4-2400 RAM, hopefully this helps:

1) definitely buy two sticks of RAM. Otherwise you'll be running in single channel mode, and you will gain greatly from getting into dual channel.

2) That setup gets bottle-necked... The gains that I see after 4 cores running prime95 are flat and/or negative depending on the FFT size. If you want a prime95 only machine, consider saving money on a 4-core processor.

Good luck!

[M344587487]

If you do build a new PC for Mprime the CPU is best utilised doing LL double checks or something else that's not PRP. Radeon VII is a beast at PRP but it can pretty much only do PRP AFAIK.

The 8700k is two generations behind intel's current lineup, I don't think the 8700k is widely available and it'll be expensive second hand as gamers cling to their platform and that's the best SKU for it. Not that the 8700k is much different to the 10600k (there's some generational efficiency gains which they spent increasing the speed at stock, but most of what intel has done is introduce extra layers of boost to grossly overpay in power for a slight opportunistic bump in productivity). To go intel new you probably need to go 9th or 10th gen, but most things intel are expensive and currently they are getting soundly beaten in most ways number crunchers might care about.

Judging by this result ( https://www.mersenneforum.org/showpo...3&postcount=61 ), a Ryzen 3600 is the way to go. This result ( https://www.mersenneforum.org/showpo...8&postcount=73 ) indicates that there may be a worthwhile bump in lower FFT tests to go for a 3900X (which for our purposes can be thought of as two 3600 stuck together with a single channel of RAM each), but at higher FFT sizes the RAM bandwidth becomes an issue. In any case the 3900X is way more expensive than the 3600, to the point where two 3600 systems with dual channel RAM each is not much more expensive and provides better throughput.

Regardless of what CPU manufacturer you pick you should get dual channel DDR4-3200 memory. Without a GPU a gold rated PSU isn't so relevant. As the occupancy of the PSU would be so low it's not in its sweet spot for efficiency, and as you're using so little power the efficiency difference likely doesn't translate to enough money to offset the initial outlay even with a 10 year lifespan.

With that in mind I've made a parts list with a Ryzen 3600, dual channel DDR4-3200, 128GB M.2 and bronze PSU for ~$440 ( https://pcpartpicker.com/list/7yXyNq ). This isn't definitive by any means, it's just a 3600 number crunching build cut to the bone. It'll last 10 years as-is, but if in the future you want to plug in a GPU say or upgrade to a beefy CPU a gold PSU like what you posted might be in order.

edit: I realise even that build is not fully cut to the bone as it has 2x8GB RAM instead of 2x4GB, another ~$30 could be saved there. I'm not well versed enough in current intel to be able to make a decent cheap build for comparison (9100F? H310 chipset?). It'd also need to be modified to fit your other requirements like front USBs.

[kriesel]

Originally Posted by M344587487

If you do build a new PC for Mprime the CPU is best utilised doing LL double checks or something else that's not PRP. Radeon VII is a beast at PRP but it can pretty much only do PRP AFAIK..

Gpuowl currently supports:

• PRP with GEC, first test or double check (zero offset only)
• LL with Jacobi check, double check (zero offset only)
• P-1 stage 1 and 2 (zero offset only)
• on Linux or Windows

Radeon VII is best used for PRP, LL, or P-1 because of its high DP performance. It can also run mfakto for TF however.

LL DC is a good use for cpu because the smaller fft lengths are likely to give better cache performance. DC is several years behind first-testing. https://www.mersenneforum.org/showpo...4&postcount=15
For first primality tests, PRP with GEC is the way to go in prime95, mprime, or mlucas, because the GEC is far superior in error detection rate over the Jacobi check's 50% detection.

[M344587487]

LL is back in gpuowl is it, interesting. P-1 yes I forgot, TF should be left alone as nvidia cards are more suited to TF.

[kriesel]

Originally Posted by M344587487

TF should be left alone as nvidia cards are more suited to TF.

Agreed, especially RX20xx / GTX16xx.