MB problem?

[guguloi]

Hello everybody,

I have an MSI KT3 Ultra2 mobo (MS-6380e) which suports up to UDMA133. I got two HDDs:
1. Maxtor DiamondMax Plus D740X (6L060J3)
2. Maxtor DiamondMax 10 (6B200R0)
Both of them are UDMA 133 capable and the OS reports them as such (UDMA Mode 6). I have the smaller HDD sharing the bus with the DVDRW (NEC ND-3500AG) while the bigger one is alone.
The problem I have is that all of the benchmarks I ran on these HDDs reported them below their counter parts and I cannot find the reason. Any idea would be greatly appreciated as I ran out of them for a while now...

Just to give you an idea of the difference, HDTach reported the following for the DM10:
Random access: 16.6ms
CPU utilization: 5%
Average Read: 47.1MB/s
Burst Speed: 71.5MB/s

while for a DM Plus9 (6Y200P0) in its database it reports:
Random access: 13.8ms
CPU utilization: 2%
Average Read: 53.1MB/s
Burst Speed: 116.5MB/s


Here are some more details about my system:
MB: MSI KT3 Ultra2 (Standard Version) KT333 chipset
CPU: AMD Athlon XP 1600+ (Palomino)
RAM: 2x256MB (PC2100)
FSB: 133MHz (all attempts to increase FSB rendered the system unstable, even with the FSB at 137MHz)
Video: Radeon 7000 (AGP x4)
FANs: intake 1x120mm, exhaust 1x120, ATX PS (with intake at the bottom), 1 HDD fan mounted on the smaller HDD blowing to the bigger one as well. The average temperature inside the case is 34C.
O/S: XP Pro Sp2

[therealwesty]

On the IDE bus all the devices share the speed of the <i>slowest</i> device connected to the specific channel. So the hard drive that is sharing the bus with your DVD writer is being forced to lower its bus speed to ATA33, looks like its the DiamondMax10. The other drive actually looks to be performing where it aught to be to me. You'd get better performance from the DM10 if it shared channels with the DMplus9.

[guguloi]

I thought about that and, in fact, the DMPlus D740X shares the same channel with the DVDRW. DM10 is on its own channel, not sharing it with anything else.
BTW, the DVDRW seems to be working at ATA66 which is not bad for an IDE I would say. Everything is reported as good as it can get by the OS, but the performance is not there.

Anyway, now that you mentioned it, I would like to get a better grip on the channel sharing: is the perfomance degraded to the lowest speed drive all the time or only when it (the lowest speed drive) is in use?

[guguloi]

Correction to the previous post: the DVDRW is in UDMA 2 Mode (ATA33). Sorry for the confusion.