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-   -   Which DDR4 RAM is best for LL on intel CPUs? (https://www.mersenneforum.org/showthread.php?t=23718)

simon389 2018-10-17 20:02

[QUOTE=mackerel;498206]Is the system primarily for doing work like this, or will it also be used for general tasks[/QUOTE]

It will be 1-4 machines 100% dedicated to LL

[QUOTE]For this particular CPU I'd keep below 4000. [/QUOTE]

What about a faster CPU? By your example would 4700mhz RAM be best for a 4.7Ghz CPU?

science_man_88 2018-10-17 20:28

[QUOTE=simon389;498207]It will be 1-4 machines 100% dedicated to LL



What about a faster CPU? By your example would 4700mhz RAM be best for a 4.7Ghz CPU?[/QUOTE]
computation section of:
[url]https://en.m.wikipedia.org/wiki/Memory_bandwidth[/url]

and performance section of:
[url]https://en.m.wikipedia.org/wiki/Central_processing_unit[/url]

plus the types of algorithms run by GIMPS, all need to be taken into account. If memory can't keep up to what the CPU can throw at it, memory speed affects performance. If you use a non parallel algorithm, that also affects performance.

mackerel 2018-10-17 21:41

[QUOTE=simon389;498207]What about a faster CPU? By your example would 4700mhz RAM be best for a 4.7Ghz CPU?[/QUOTE]

I said for a quad core CPU (with dual channel ram). If you went 6 core CPU for example, you're going to want much faster ram if running dual channel.

Also, don't take it too exactly, it is ball park indicative of where things switch from being more CPU limited to more ram limited. It isn't linearly related to one or the other in that region, so even if you're not at the ideal point, you don't lose as much going either side. As you're building for this task, you'd probably be better off optimising for overall system performance vs cost. I can't recommend really high speed ram (4000+) due to the uncertainty of its compatibility.

I still think if you went with the quad core, look around 3200 or a bit faster if the price difference isn't too much. Presuming you wont really need more than 8GB of ram, so 2x4GB in dual channel would keep costs down. It will probably be difficult to find higher speed modules in 4GB capacity anyway.

kladner 2018-10-18 00:12

I don't know what those high-end DRAM sticks cost. I have gotten the impression that your are willing to more upscale on the memory and CPU. Consider boards and CPUs which support 4 RAM channels. RAM running at 3200mhz takes on new meaning with twice the channels.

There has to be a cross-over point for the performance/price of ultra-fast RAM, versus the performance/price of going to an x99 family chipset, with 'normal' high speed RAM (3200-3600mz), and an appropriate CPU. I bet the average hex-core Intel chip with quad channel would not be as RAM-limited as a fast quad core with dual channel.

Prime95 2018-10-18 01:09

Seriously, you are better off with "commodity parts" rather than "enthusiast parts". You will get much more throughput buying six mundane systems rather than four high-end systems.

I highly recommend reading the thread on George's dream build. Memory prices have doubled since then but the principles still apply. Today that translate into 4-core i3 parts with memory in the 3200 to 3600 range.


If you insist on buying 4700 memory you should pair that with a six-core CPU.

irowiki 2018-10-18 16:57

[QUOTE=Prime95;498215]Seriously, you are better off with "commodity parts" rather than "enthusiast parts". You will get much more throughput buying six mundane systems rather than four high-end systems.
[/QUOTE]

This is interesting for me, as the wife is putting together a new gaming system, and wanted to go with a fairly recent AMD Ryzen, and I was trying to talk her into a high end i5/i7 since the Intels seem to run prime95 better.

So basically I should take the money saved from her going AMD and just buy an "older" i5/i7 system and it would probably combined do more than just one beefy computer.

retina 2018-10-18 17:16

[QUOTE=irowiki;498243]So basically I should take the money saved from her going AMD and just buy an "older" i5/i7 system and it would probably combined do more than just one beefy computer.[/QUOTE][url=https://en.wikipedia.org/wiki/Diminishing_returns]Yup[/url]

science_man_88 2018-10-18 17:54

[QUOTE=irowiki;498243]This is interesting for me, as the wife is putting together a new gaming system, and wanted to go with a fairly recent AMD Ryzen, and I was trying to talk her into a high end i5/i7 since the Intels seem to run prime95 better.

So basically I should take the money saved from her going AMD and just buy an "older" i5/i7 system and it would probably combined do more than just one beefy computer.[/QUOTE]

[url]https://en.m.wikipedia.org/wiki/List_of_interface_bit_rates[/url] may also be an interesting read for you.

M344587487 2018-10-19 11:32

[QUOTE=irowiki;498243]This is interesting for me, as the wife is putting together a new gaming system, and wanted to go with a fairly recent AMD Ryzen, and I was trying to talk her into a high end i5/i7 since the Intels seem to run prime95 better.

So basically I should take the money saved from her going AMD and just buy an "older" i5/i7 system and it would probably combined do more than just one beefy computer.[/QUOTE]


A new Ryzen or 2nd hand older i5/i7 are your best options. In all cases you'll be limited by dual channel RAM and the new intel parts are far too expensive to be a bang for buck option (even the previous gen new parts are expensive, more expensive than they already were due to recent price hikes).


As for your wife's gaming PC Ryzen is a good choice, most recommend 2600(X) for gaming but there's an argument for a 2700(X) if the price difference is not large. Higher models come with better stock coolers which makes a difference in how high and long the chip can boost. If you were planning to get a third party cooler for a 2600 I'd think about just getting a 2600X or 2700X instead (I think 2600 comes with low profile wraith spire, 2600X and 2700 come with normal wraith spire, 2700X comes with wraith prism which is comparable to a cheap third party solution).

irowiki 2018-10-20 00:38

[QUOTE=M344587487;498281]

As for your wife's gaming PC Ryzen is a good choice, most recommend 2600(X) for gaming but there's an argument for a 2700(X) if the price difference is not large. Higher models come with better stock coolers which makes a difference in how high and long the chip can boost. If you were planning to get a third party cooler for a 2600 I'd think about just getting a 2600X or 2700X instead (I think 2600 comes with low profile wraith spire, 2600X and 2700 come with normal wraith spire, 2700X comes with wraith prism which is comparable to a cheap third party solution).[/QUOTE]

I have a giant cooler ( [URL="https://smile.amazon.com/Cooler-Master-Hyper-212-RR-212E-20PK-R2/dp/B005O65JXI/ref=sr_1_1?s=pc&ie=UTF8&qid=1451098299&sr=1-1&keywords=Cooler+Master+212+EVO"]link[/URL] ) on my FX-8350, running flat out with prime95 it never gets above 100F, so I'll probably get her the same unless there's something better now. Unless we get the 2700x, then we'll try that one!

Thanks for the Ryzen feedback, it helps a lot!

Mark Rose 2018-10-22 17:02

[QUOTE=irowiki;498243]So basically I should take the money saved from her going AMD and just buy an "older" i5/i7 system and it would probably combined do more than just one beefy computer.[/QUOTE]

Haswell (4000 series) or better though. You'll get much more throughput/watt.


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