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Old 2011-01-13, 17:32   #1
Rodrigo
 
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Default Which of these CPUs is most productive?

Hello,

I'm thinking of upgrading the CPU on my main PC, and I'm keeping an eye to the various candidates' potential contributions to GIMPS.

I currently have the Pentium Dual CPU E2200. Which of the first three processors on this chart (http://ark.intel.com/Compare.aspx?ids=42811,41495,33911,37251,33925,) would be the most productive in terms of LL work? I found GIMPS throughput data for some but not others.

The first thing one looks at when comparing is the clock speed, of course, but I know that other factors are involved. So (for instance) is it better to go with the 3.33GHz chip that has a 2MB cache, or the 3.06GHz chip with a 3MB L2 cache? How about the 3.16GHz CPU, nominally slower than the first one but with a 6MB cache and a 1333MHz system bus? I'm not sure how to weigh these various factors against each other.

Thanks for any insight you might provide!

Rodrigo
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Old 2011-01-13, 20:51   #2
mdettweiler
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Probably the one with 6MB cache would be best suited for GIMPS work. LL tests of the size GIMPS generally does are highly cache-bound, so I would expect the significantly extra cache of the 3.16GHz CPU to outweigh the faster clock speeds of the 3.3Ghz.

I'm not sure exactly what effect system bus speed has on LL tests, but at the very least can imagine that more is better in this case. So the 3.16Ghz CPU definitely sounds like the way to go.

Note that the E8500 currently costs $200 on Newegg, the E7600 $150, and the E6800 $100. For just $100 more than the cost of the E8500, you can build an entire new system based on an AMD Athlon II X4, which, depending on which Core 2 you're comparing it to, could be a little faster or a little slower per-core, but regardless of that, would give you a lot more crunching power because of the two additional cores. (I actually put together such an example system for a friend just yesterday...if you'd like I can post the specs. You can also switch out the X4 for an X3 or X2 in the same configuration, which subtracts about $20 per core sacrificed.)
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Old 2011-01-13, 22:28   #3
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mdettweiler,

I'd be curious to see the specs on the system you built!

My thinking was in terms of upgrading the CPU, but I'm *almost* at the point where I could try building a PC, and you just might tip me over the edge.

Thanks much for the info on the three chips -- that was very helpful.

Rodrigo
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Old 2011-01-13, 22:40   #4
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Okay, here's the specs:
Quote:
Processor:
AMD Athlon II X2 240 Regor 2.8GHz 2 x 1MB L2 Cache Socket AM3 65W Dual-Core Processor ADX240OCGQBOX
http://www.newegg.com/Product/Produc...82E16819103688 - $56.99
OR
AMD Athlon II X3 445 Rana 3.1GHz 3 x 512KB L2 Cache Socket AM3 95W Triple-Core Desktop Processor ADX445WFGMBOX
http://www.newegg.com/Product/Produc...82E16819103872 - $77.00
OR
AMD Athlon II X4 635 Propus 2.9GHz 4 x 512KB L2 Cache Socket AM3 95W Quad-Core Desktop Processor ADX635WFGIBOX
http://www.newegg.com/Product/Produc...82E16819103702 - $97.99

Motherboard:
BIOSTAR A880G+ AM3 AMD 880G HDMI Micro ATX AMD Motherboard
http://www.newegg.com/Product/Produc...82E16813138283 - $54.99

RAM:
GeIL Value PLUS 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10660) Desktop Memory Model GVP34GB1333C9DC
http://www.newegg.com/Product/Produc...82E16820144478 - $39.99

Hard Drive:
SAMSUNG Spinpoint F4 HD322GJ/U 320GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
http://www.newegg.com/Product/Produc...82E16822152244 - $42.99

DVD Burner:
LG Black 24X DVD+R 8X DVD+RW 16X DVD+R DL 24X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM SATA DVD Burner - Bulk - OEM
http://www.newegg.com/Product/Produc...82E16827136177 - $19.99

Case:
Xigmatek ASGARD II B/O CPC-T45UE-U01 Black / Orange 0.8 mm SECC / Aluminum and Aluminum Mesh Bezel ATX Mid Tower Computer Case
http://www.newegg.com/Product/Produc...82E16811815006 - $29.99

Power Supply:
Linkworld Linkpower ATX-550 LPG12-35-p4 550W ATX 12V REV. 2.01 Power Supply I-7 ready
http://www.newegg.com/Product/Produc...82E16817165041 - $26.99

----------------------------------
Price with X2 CPU: $271.93
Price with X3 CPU: $291.94
Price with X4 CPU: $312.93

subtract $20 for 2GB RAM
subtract $8 for 160GB hard drive
The components were chosen to optimize crunching value, yet also for the system to be suitable for everyday use. If it's to be a dedicated crunching machine, you could save $20 by going with 2GB of RAM (though the 4GB could come in handy for P-1 jobs), and another $8 by going with a 160GB hard drive (the cheapest available on Newegg at this time) since a dedicated cruncher doesn't need much hard drive space.

Note also that this configuration is fully GPU-ready: the 550W power supply should be able to handle a GTX 460 pretty well. (This power supply is actually a pretty good deal...you'd only save a few bucks by going with a 400W or 300W. Normally I would be hesitant to recommend such a cheap PSU, but I've had good results with this brand before.)
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Old 2011-01-14, 21:34   #5
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Default flash drives

I use flash drives rather than hard drives for my dedicated chrunchers, usually a 4 gig is plenty of storage for operating system and data.

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Old 2011-01-14, 23:49   #6
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Quote:
Originally Posted by mdettweiler View Post
The components were chosen to optimize crunching value, yet also for the system to be suitable for everyday use. If it's to be a dedicated crunching machine, you could save $20 by going with 2GB of RAM (though the 4GB could come in handy for P-1 jobs), and another $8 by going with a 160GB hard drive (the cheapest available on Newegg at this time) since a dedicated cruncher doesn't need much hard drive space.

Note also that this configuration is fully GPU-ready: the 550W power supply should be able to handle a GTX 460 pretty well. (This power supply is actually a pretty good deal...you'd only save a few bucks by going with a 400W or 300W. Normally I would be hesitant to recommend such a cheap PSU, but I've had good results with this brand before.)
mdettweiler,

That is fabulous! I'm tempted to try building my own system. We've been thinking of buying a PC to serve as a DVR ("home theater PC"), and the computer you describe would fit the bill nicely. (Except that I would get a bigger hard drive.) You don't think that running Prime95 surreptitiously alongside the TV tuner and recording functions would affect performance noticeably, do you?

What OS did you put on it?

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Old 2011-01-15, 00:00   #7
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Quote:
Originally Posted by Harvey563 View Post
I use flash drives rather than hard drives for my dedicated chrunchers, usually a 4 gig is plenty of storage for operating system and data.

Harvey,

When you say flash drive, do you mean a solid state drive (SSD), or an actual USB thumb drive? And if it's a thumb drive, if not OS or data then what do you do with (or put on) the hard disk?

I'd be curious to see the specs on this system!

Rodrigo
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Old 2011-01-15, 00:02   #8
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Quote:
Originally Posted by Rodrigo View Post
mdettweiler,

That is fabulous! I'm tempted to try building my own system. We've been thinking of buying a PC to serve as a DVR ("home theater PC"), and the computer you describe would fit the bill nicely. (Except that I would get a bigger hard drive.) You don't think that running Prime95 surreptitiously alongside the TV tuner and recording functions would affect performance noticeably, do you?

What OS did you put on it?

Rodrigo
I would expect Prime95 to not have any deleterious effect on system performance. Particularly as long as the machine has a dedicated GPU of some sort (which you'd probably want for a home theater PC), Prime95 shouldn't be a problem even under heavy multimedia use.

One thing I forgot to mention earlier is that for about $100 more, you can get a Phenom II X6 CPU (the 1055T is the cheapest, though for just a bit more you can get its more upscale cousins with progressively higher clock speed). Right now, the X6's are really the best "bang for the buck" out there when it comes to crunching power. The only reason why I didn't include it in the above listing is because my goal was to see "how cheap can you build a decent PC for?". If the extra $100 is within your price range, I would definitely swap out the X4 for an X6 (it will also work with the same configuration) considering how much additional power you get.

Regarding OS, FYI I didn't actually build this machine (or even buy any of the parts); I put it together as an entirely hypothetical exercise. So I didn't give much consideration to the OS. For a dedicated crunching machine, I would recommend Linux (Ubuntu is a good, easy distribution if you're not too familiar with Linux); but for a home theater PC you'd want to go with Windows 7, probably Home Premium version. And, of course, whatever the OS, definitely get a 64-bit version, as nowadays those can do anything a 32-bit version can and they're rather faster on TF (a little faster on LL-like work too, IIRC, though not as much so).
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Old 2011-01-15, 00:10   #9
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Quote:
Originally Posted by Rodrigo View Post
Harvey,

When you say flash drive, do you mean a solid state drive (SSD), or an actual USB thumb drive? And if it's a thumb drive, if not OS or data then what do you do with (or put on) the hard disk?

I'd be curious to see the specs on this system!

Rodrigo
I'd guess an SSD. Taking a quick look at Newegg, I see that you can get an 8GB SSD for about the same price as the hard drive in my hypothetical configuration--for a dedicated cruncher, that would definitely be the way to go. (Same price, but MUCH faster, and a dedicated cruncher doesn't need much space.)

Note that most of the cheaper SSDs available have a 2.5" form factor, rather than the standard 3.5" that desktop hard drives usually have, so that they can fit in laptops as well. You'd need to get spacers (you can probably pick them up from your local computer store very cheaply) to fit them into a desktop chassis. The cable connections, though, should be compatible since it's SATA. (If it was IDE, you'd need an adapter as laptops use a different kind of IDE interface.)
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Old 2011-01-15, 00:18   #10
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Quote:
Originally Posted by mdettweiler View Post
I would expect Prime95 to not have any deleterious effect on system performance. Particularly as long as the machine has a dedicated GPU of some sort (which you'd probably want for a home theater PC), Prime95 shouldn't be a problem even under heavy multimedia use.

One thing I forgot to mention earlier is that for about $100 more, you can get a Phenom II X6 CPU (the 1055T is the cheapest, though for just a bit more you can get its more upscale cousins with progressively higher clock speed). Right now, the X6's are really the best "bang for the buck" out there when it comes to crunching power. The only reason why I didn't include it in the above listing is because my goal was to see "how cheap can you build a decent PC for?". If the extra $100 is within your price range, I would definitely swap out the X4 for an X6 (it will also work with the same configuration) considering how much additional power you get.

Regarding OS, FYI I didn't actually build this machine (or even buy any of the parts); I put it together as an entirely hypothetical exercise. So I didn't give much consideration to the OS. For a dedicated crunching machine, I would recommend Linux (Ubuntu is a good, easy distribution if you're not too familiar with Linux); but for a home theater PC you'd want to go with Windows 7, probably Home Premium version. And, of course, whatever the OS, definitely get a 64-bit version, as nowadays those can do anything a 32-bit version can and they're rather faster on TF (a little faster on LL-like work too, IIRC, though not as much so).
Thanks mdettweiler, you've given me a lot to chew on... plus a fun long session browsing on Newegg!

Rodrigo
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Old 2011-01-15, 00:27   #11
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Quote:
Originally Posted by Rodrigo View Post
When you say flash drive, do you mean a solid state drive (SSD), or an actual USB thumb drive? And if it's a thumb drive, if not OS or data then what do you do with (or put on) the hard disk?
A USB thumb drive. Most modern BIOS'es can boot from the thumb. They are way cheaper than a mechanical and use less power. If the machine is networked the critical data can be backed up easy. If you can boot from LAN, then you don't need that either. PrimeMonster used to boot a *nix from LAN and ran it from a RAM drive. Each node had a spot on the server's HDD for data storage.
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