When I run "Raptest" on my C drive the results in writing speed vary from 4 to 34 Mb/sec. Everything is "clean"(defrag...) The disk has 33% free space. Disabling virusscan doesn't change the allways changing results. I think my disk is "getting old"(though no bad sectors!) and gets out of tolerance so that the packet writing applied in Raptest has to be redone sometimes. Any advise?

Could it be some kind of thermal calibration causing the slow down?

1. I don't know "raptest", not every test program ou there is good or reliable

2. harddisks always change in throughput speed since more data is packed in the inner ring than the other ring on the same space

3. does this test you are running have a name? You normally have average tests, maximum throughput etc. etc.

Rob, Raptest/Rextest is pretty well accepted in the DV amateur world. You can free download it from http://www.canopus.us/US/products/free_utilities/pm_free_utilities.asp.
Jeff, the HDD is not that old so it's not a type that needs TC.

Is there any other device on the SAME cable as this IDE drive?
What operating system are you running?

Yes Rob, a CDRW is connected as a slave on the primary IDE channel. The OS is XPpro SP2

I think you are seeing the reason it is advisable not to use the C drive for video. Windows has absolute control over that drive and will go to it at random times, locking out any other activity. That may well be why you see such a variation in the speed.

RapTest is indeed a good indicator of drive speed. I've been using the RexTest for the past 6 years with no problems. They are essentially the same program.

Thanks Mike, could well be the reason and maybe XP is even more active in claiming my C-drive than W2k used to be. The dips were there too but never below 15Mbs

Although XP might do that, it really shouldn't. I would first
disconnect the CDRW from the primary IDE channel and run the
tests again. I'm pretty sure your drive is running in a lower UDMA
mode due to this burner being on there. Either move it to the
other IDE channel or get some extra IDE channels with a PCI
card like the ones from Promise or Adaptec.

Rob I will "play"with it and report later on. B.t.w. the C drive is on the primary master (CS) and the controller for that channel shows Ultra DMA 5. There are more devices installed on the PC and one of them (a videodisk) is on a PCI card (HTP366 from Abit)