Table 1:  | Drive specifications summary for 1000 and 640 Gbyte models | ||
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Drive specification  | ST31000333AS  | ST3640323AS  | |
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Formatted capacity (512 bytes/sector)*  | 1000 Gbytes  | 640 Gbytes  | |
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Guaranteed sectors  | 1,953,525,168  | 1,250,263,728  | |
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Heads  | 
  | 6  | 4  | 
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Discs  | 
  | 3  | 2  | 
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Bytes per sector  | 512  | 
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Default sectors per track  | 63  | 
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Default read/write heads  | 16  | 
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Default cylinders  | 16,383  | 
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Recording density  | 1300 kbits/in max  | 1250 kbits/in max  | |
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Track density  | 
  | 182 ktracks/in avg  | 
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Areal density  | 
  | 228 Gbits/in2 avg  | 219 Gbits/in2 avg  | 
Spindle speed  | 
  | 7,200 RPM  | 
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Internal data transfer rate  | 1520 Mbits/sec max  | 1460 Mbits/sec max  | |
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Sustained data transfer rate OD  | 120 Mbytes/sec max  | 115 Mbytes/sec max  | |
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I/O   | 300 Mbytes/sec max  | 
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ATA   | PIO modes   | 
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  | Multiword DMA modes   | 
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  | Ultra DMA modes   | 
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Cache buffer  | 
  | 32 Mbytes  | 
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Height (max)  | 
  | 26.1 mm (1.028 inches)  | 
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Width (max)  | 
  | 101.6 mm (4.000 inches) +/- 0.010 inches  | 
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Length (max)  | 
  | 146.99 mm (5.787 inches)  | 
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Weight (typical)  | 630 grams ( 1.389 lb.)  | 543 grams (1.199 lb.)  | |
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Average latency  | 4.16 msec  | 
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20 sec max  | 
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Standby to ready  | 15 sec max  | 14 sec max  | |
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<1.0 msec typical read;  | <0.8 msec typical read;  | ||
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  | <1.2 msec typical write  | <1.0 msec typical write  | 
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Average seek, read  | <8.5 msec typical  | 
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Average seek, write  | <9.5 msec typical  | 
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Startup current (typical) 12V (peak)  | 3.0 amps  | 
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Voltage tolerance (including noise)  | 5V +10% /   | 
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  | 12V +10% /   | 
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Ambient temperature  | 0° to 60°C (operating)  | 
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Temperature gradient  | 20°C per hour max (operating)  | 
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  | 30°C per hour max (nonoperating)  | 
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Relative humidity  | 5% to 95% (operating)  | 
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  | 5% to 95% (nonoperating)  | 
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Relative humidity gradient  | 30% per hour max  | 
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Wet bulb temperature  | 37.7°C max (operating)  | 
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  | 40.0°C max (nonoperating)  | 
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Altitude, operating  | 
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Altitude, nonoperating  | 
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(below mean sea level, max)  | 
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Operational Shock  | 70 Gs max at 2 msec  | 
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300 Gs max at 2 msec  | 
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4  | Barracuda 7200.11 Serial ATA Product Manual, Rev. B |