I was initially having problems doing the CDSpeed benchmark test on my Benq DW1640. On the NEC 3540A and Liteon SOHO1673S@1693S it wasn't so bad.
Basically it would get up to about 12x read speed and then going back down again rather like a DL speeds up and slows down at the midpoint. I eventually tracked the problem down to the SPTD driver I had installed with Daemon tools. After uninstalling that the slowdown halfway through went away.
However I was having lots of spikes and iregular speed curves. What I have found is that if I kill near enough every background process I can achieve a smooth read curve in all my drives (But in particular the DW1640 which is my favorite drive). PIE/PIF scans work fine at 8x 1ECC and using Solidburn on known media I get still better scores than with the default strategies.
The problem only occurs when benchmarking. I have not done benchmarks for a while. In fact not since I upgraded my entire system last year. So this is new to me. I don't recall my previous setup being this way. Task Manager shows no excessive background processes hogging any CPU. In fact CPU usage is minimal (1% on 2-3 processes). I tried setting affinity and priority on CDSpeed but it did not seem to make any difference. I still get spikey uneven benchmark curves unless I kill nearly every background process. It does not appear to be one troublesome process either. It appears to be the more background processes running the more spikes and uneven the curve.
Using MS standard IDE drivers (XP Pro SP2) and DMA is enabled and showing as running. I have tried different cables and swapping controllers but it made no difference. The biggest difference was kill nearly all processes.
Is this normal?
System is an Asus P5N-E-SLI with Intel E6600 and twin 7600GT's plus 2 SATA drives.