quoted

Any results on the test with the other drive?

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The test results with 2 WD drives,

1. Desktop 500GB 7200 rpm WD5000AKX drive
      [good S8005GM2NR board] read speed - 127 Mb/s
      [good S8005GM2NR board] write speed - 124 Mb/s
      [bad S8005GM2NR-LE] board read spead - 127 Mb/s
      [bad S8005GM2NR-LE] board write speed - 124 Mb/s

2. Mobile 250GB 5400 rpm WD2500BEVS
      [good S8005GM2NR board] read speed - 57 Mb/s
      [good S8005GM2NR board] write speed - 55 Mb/s
      [bad S8005GM2NR-LE] board read spead - 37 Mb/s (!)
      [bad S8005GM2NR-LE] board write speed - 30 Mb/s (!)

So at least the perfomance dropped with different drive too and the drop is
nearly 20Mb/s.

I've made another test, trying to exclude the SP52100 - I've used the
external PCI SATA controller from Silicon Image Sil3112A, so the two
drives - Hitachi and WD were connected to PCI SATA board instead of
onboard SP5100, test results below :

1. Hitachi HTS725050A7E630 500GB drive
      [good S8005GM2NR board] read speed - 88 Mb/s
      [good S8005GM2NR board] write speed - 80-91 Mb/s (!)
      [bad S8005GM2NR-LE] board read spead - 35 Mb/s
      [bad S8005GM2NR-LE] board write speed - 0.9 Mb/s (!)

2. Desktop 500GB WD5000AKX drive
      [good S8005GM2NR board] read speed - 98 Mb/s
      [good S8005GM2NR board] write speed - 85 Mb/s
      [bad S8005GM2NR-LE] board read spead - 96 Mb/s
      [bad S8005GM2NR-LE] board write speed - 87 Mb/s

So the low write perfomance do not depends even from SATA controller,
but depends from the HDD and moherboard combination. Can we see (or
debug) what is happenning on bad  S8005GM2NR-LE motherboard during
write ?

-- 
Rus