Mersenne Rig

[kracker]

Originally Posted by simon389

So, if I'm reading this correctly, the general consensus is better RAM and PSU. Can you link to a few NewEgg pages for me to order?

Can my mobo use DDR3-2400 Ram?

I'm not going to crunch with the GPU, CPU only. Influenced by this post: http://www.overclock.net/t/1212493/f...o-folding-24-7

Trying to keep the power bill as low as possible. Planning on going headless linux CPU only, though I am open to being convinced :D

What is your budget range?

[Prime95]

Originally Posted by danaj

The 3930K would give you an extra 2 cores and double the memory bandwidth, but that would probably be outweighed by the missing Haswell new instructions for those apps that use them.

Memory bandwidth is more important than the new instructions. However, Intel charges a pretty penny for those 6-core beasts.

[Prime95]

Originally Posted by simon389

Can you link to a few NewEgg pages for me to order?

My Haswell components are listed in the 38th post of http://www.mersenneforum.org/showthread.php?t=17982

Prices and deals change though, so you are apt to find more cost-efficient components if you search.

[TheMawn]

Hi! Glad to hear of a new member with commitment. Some of my comments have been touched on already but I will try to elaborate a bit.

• Lucas Lehmer tests will in fact not take advantage of hyperthreading which will save you as far as money and heat is concerned; heat in particular, since you want to overclock. Are we talking some moderate 4.0 GHz or a more serious 4.6+ GHz overclock? Make sure your cooling is up to the task. A Hyper 212 is a good start, though my i5-3570k is at 4.6GHz on an H80i and the temperatures are about as high as I would like already.
  
• Memory bandwidth is a huge factor, especially with a faster architecture and this is further yet amplified by the fact that you want to overclock. I have this 2400 MHz memory, myself and it's already not quite enough for a 3570k @ 4.6 GHz on four cores. It could use about 20% more speed. Part of me is salivating over this 2666 MHz memory.
  
• To get around the memory bandwidth limitation, you may wish to consider the "enthusiast" line of processors which use quad channel memory instead of dual channel memory. I don't know that the speeds can be matched, but you're doubling the bandwidth already, so even a slight decrease in frequency would allow you to run six workers instead of four, and have them completely fed.
  
• I would urge you to consider GPU computing. A GPU doesn't consume as much power as you think. My GTX 660 Ti consumes roughly 105W and is seven times more productive than my overclocked i5, in GHz-Days terms. Not nearly as good for LL tests but amazing for trial factoring.
  
• A better power supply might be a good idea. Particularly if you plan to run a GPU or two, or three. I'm running an i5, a GTX 670 and a GTX 660 Ti, all overclocked to their limits, on a 750W and I think I have room to spare. I have seen Three Way SLI GTX 660 Ti done on 750W.
  
• Biggest consideration is budget. My guess is you know this very well already.

For quad channel RAM, hexacore juiciness and a much bigger bill from Newegg, get this quad-channel set of memory for example. I don't know if 2400 MHz will be attainable or even necessary. Also, you might want a powerful CPU cooler since your CPU will now have a TDP likely nearer 150W than 100W.

Note the processor and motherboard will also run you $200 more than their non-enthusiast lineup equivalents.


For the standard dual channel setup, get the 2666 MHz RAM I mentioned earlier, and grab a non-hyperthreaded CPU because it will not help you at all to have hyperthreading. I once felt like an i7 sounded a LOT cooler than an i5 but $100 in your pocket seems pretty cool too... You could get a slightly less crazy cooler.


If you are sure you don't want to use a GPU, then 450W is enough, if you're confident of the quality.


If you are convinced to go the GPU route, you may want to consider how many you would like, and which ones you would like.

The Titans are some pretty scary badasses but are also exceedingly expensive and only cost-effective in the LL test departments. For the price of one Titan you can build a separate GPU-less system and run LL's on it instead.

A more cost-effective GTX x50, x60 or x60 Ti can run some pretty serious Trial Factoring for around $200 apiece.

You will need to know how many PCI-E plugs are on the cards you want. This power supply has eight PCI-E cables which would support up to four GTX 660Ti (if you can find room for them, lol). This one would hold two GTX 660 Ti or 4 GTX 650 (again, room for four cards is tough, and you also need the motherboard to support it).

450W + 100W per mid end GPU is loads of power.

[kracker]

Just one thing, I think it is a terrible idea to buy a Kepler card only for compute, if you decide on a GPU I've heard ebay etc is a good place for Fermi cards, otherwise I would go AMD...

Yes, it all depends on your budget, you can go as high as you want or quite low, frankly.

[kladner]

Originally Posted by kracker

Just one thing, I think it is a terrible idea to buy a Kepler card only for compute, if you decide on a GPU I've heard ebay etc is a good place for Fermi cards, otherwise I would go AMD...

Yes, it all depends on your budget, you can go as high as you want or quite low, frankly.

There are definitely deals to find on Ebay for 500 series GPUs. I'm now running a GTX 570 and a 580 courtesy of Ebay, although the 570 is an RMA replacement for my original purchase. (At least in the US, Gigabyte honors warranties for subsequent buyers of a card).

If two or more GPUs are in question, spacing and cooling get far more critical. I have slots for more than two, but one is not usable for a 2+ slot card unless you have a full tower case. The bottom-mounted PSU gets in the way in a mid tower. If the GPUs dump hot air inside the case, you really want a high air flow setup.

[henryzz]

If you are going for performance/watt then go for a low power quad. You also won't have to worry about memory so much. The trouble then becomes space as you will need more pcs.

[simon389]

Alright why don't we do this. Many of you seem to have a real solid understanding of the hardware needed to create this machine, so I'll let you build it.

Here is my goal: build a fast, headless, overclocked LL cruncher

1. Need a (i) CPU, (ii) Mobo, (iii) PSU, (iv) Ram, & (v) watercooler
2. No video crunching
3. Silent (or near silent). Small apartment, so this is going in my living room.
4. Minimal monthly electric bill
5. $650 budget

I have experience building computers, so none of that should be a problem. I have a 500GB drive laying around for the HDD, as well as big case, screws, thermal grease, etc. I also have experience overclocking (used to use peltier ).

Can somebody suggest i-v above, if I need to wait for the September processor launch, and I'll order it off newegg.

Originally Posted by Prime95

My Haswell components are listed in the 38th post of http://www.mersenneforum.org/showthread.php?t=17982

Prices and deals change though, so you are apt to find more cost-efficient components if you search.

This actually feels in the ballpark of what I want. Would you edit it for my particular situation above?

[paulunderwood]

Get what you spec'd before (4770k, MSI board, etc) except get 2400MHz RAM. I run mine with a Huntkey 300W, gold rated -- I must be hitting the sweet spot for power usage.

[simon389]

Is there any benefit of sticking with an i7? Or is there no real difference aside from hyperthreading, which Prime95 can't use anyways?

[kladner]

More cache? More cores?