Sunday, August 02, 2009

New Atom System

The latest computer system to come to life here at AA6E is based on the Intel Atom 230 processor. The Atom (out for a year now) uses the latest 45 nm fab technology for a chip that is optimized for low power consumption, but it supports either 32- or 64-bit operating systems and hyperthreading, giving the appearance of a dual-core system to the OS.

I bought the Intel D945GCLF board, which has the mini-ITX format -- it's really small compared to my other ATX and mini-ATX systems.

Intel D945GCLF Motherboard and Atom 230 Processor

The board mounts nicely in a spare Mini-ATX computer case, with all kinds of room to spare. I attached an older 20 GB hard drive and DVD to the legacy IDE port. Eventually, I may repackage the system into a smaller case, with more modern IO devices. But one of the nice features of the motherboard is its support for ancient interfaces -- Serial, Parallel, PS/2 Mouse, keyboard, and IDE, along with newer SATA, USB, etc.

The focus for me was low power consumption and low out-of-pocket cost. The CPU is supposed to require only 4 W and the basic board was $64 at Amazon, including CPU but no RAM. The major glitch building the system was that my numerous old PC power supplies did not supply the ATX12V connector (the 4 pin 12 V CPU power connector) or any SATA-style connectors. So, while I might have been able to wire up some connectors to use with an older supply, I sprang for a new unit. Selecting one was not as easy as it might have been. The power demand is minimal (under 100 W), but if you want "quality" (efficiency, power factor, noise filtering), those features are promoted for larger supplies. I ended up with a 500 W, $35 unit.

Performance

A thorough review of an Atom 230 system is available at Tom's Hardware. I did some testing that is more specific to my environment, comparing it with other systems here.

A favorite benchmark, which works with multi-threaded systems, is to "make" the hamlib system from source. (I am a Hamlib developer.) The make "-j" switch lets you specify how many parallel threads to divide the workload into. This is a useful test for some kinds of programming work, but it is hardly representative of all possible applications.

Pentium III 800 MHz
(This is the one that the new Atom system will replace.)
  • Idle power: 112 W (AC at wall plug)
  • Make (single thread) : 483 sec.

Athlon XP 2000+
  • Make (single): 239 sec

Core i7 920 (See prior article here and here.)
  • Idle power: 100 W
  • Full CPU load: 150 W
  • Make (-j 1): 41.8 sec
  • Make (-j 8): 17.3 sec
  • Make (-j inf.): 16.1 sec

Atom 230
  • Idle power: 40 W
  • Make (-j 1): 276 sec
  • Make (-j 2): 229 sec (showing improvement by hyperthreading)
  • Make (-j inf.): requires excessive virtual memory, never completes

Conclusion

The Atom-based system works very nicely for my application: running all my ham radio operations - digital modes (fldigi), logging (xlog), transceiver control, etc. The system has a responsive "feel" under Ubuntu that is equal to anything I was using before my Core i7 system came along. The low operating power and silent operation are pluses, and the small board size would be handy if I put it into a smaller case. Cheap is good, too.

Update:
BOINC benchmarks, Atom 230 (40 W)
612 floating point MIPS (Whetstone) per CPU
1530 integer MIPS (Dhrystone) per CPU

BOINC benchmarks, i7 920 (150 W)
2450 floating point MIPS (Whetstone) per CPU
5654 integer MIPS (Dhrystone) per CPU

Since the i7 920 has 8 "processors" (4 cores) and the Atom 230 has 2 "processors" (1 core), the i7 is much better in CPU MIPS per Watt.
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