AHCI + caching of disk reads/writes = random speed drops

[nitrobg]

I enabled AHCI today on my computer, installed drivers and everything else I need, but suddenly I realized that utorrent had some upload issues - people were successfully connecting to me, however nothing was uploaded. Once in every like 10 minutes speed went up for few seconds, then it dropped down to zero again. So I started searching the forums for people with similar issues, and I've found that the issue is in caching of disk reads for uploading and disk writes for downloading. I disabled caching of disk reads and speed went up, but it is accessing my hard drive more aggressively without caching enabled.

The question is - is this intended, is it a bug, or it's normal for AHCI mode?

OS: Win7 x64 RTM

MB: Gigabyte P35-DS3L

CPU: does it matter?

HDDs: Seagate ST3120026AS, Maxtor 6B300S0

[nitrobg]

Bump. Any ideas?

Disabling AHCI fixed the issue, however is it possible to fix it without disabling this?