Hard drive CPU utilization problem

[slim_lim]

I have this oldish system: Win98, Abit BH6 mobo, Celeron 900@1008, 2 Quantum HDDs as masters on each channel and a HP 4x CDRW as slave on the secondary channel. Whenever I try to access any of these drives in any way, CPU utilization jumps to 100% as reported by the System Monitor: Kernel Proceesor utilization. If I copy some files, it stays at 100% until the copy is fnished. This makes the system sluggish during disk access, and in games caused 'hiccups'. I checked that DMA is enabled on all drives. The weird thing is that HDTach shows low CPU utilization -- below 5% and appropriate UDMA burst rate of 33 mbps, but running System Monitor alongside it shows 100% during the test. I tried another CPU measurement utility and still get 100% usage. Any ideas what's going on here?
I have no other system handy to compare it to. Could someone, preferably with a similar setup, try copying some files and see what their CPU usage is? Much appreciated.

[engjohn]

well it would not supprise me if you are getting 100% usage. IDE uses the CPU as the controller cpu and you can expect some useage. Things will seem slugish, it is only a 33MBs controller. Get yourself a ultra66/100/133 drive controller card (some can be had for $40.). If your drives support 66/100/133 you will see a performance increase.

[slim_lim]

I doubt a new controller would improve things. My drives are UDMA 33 and 66 respectively (BIOS sees them both as UDMA33 since that's the max mobo supports), and even so the transfer rate for the faster one maxes out at ~22 mbps, well below the 33 mbps max transfer rate, so that's not the bottleneck. Anyway, my issue is not with the transfer rate but with the CPU usage. I thought DMA was supposed to allow disk access by the chipset rather than CPU, so why is my CPU still getting used 100%? and why the wild discrepancy (<5% vs. 100%) between CPU usage reported by HDTach and System Monitor?

[JimmyG]

I didn't see where you told us how much ram the computer has. If you are running with 16 or 32 mb of ram the same thing would happen. I have an old k6-2 300mhz and I increased from 32mb to 256mb of ram and saw a startling improvement is speed.

[slim_lim]

384mb sdram, so I doubt it's the RAM. Can someone please do me a favor and try copying some files under Win98 and see what the CPU load is?