I have a netbook (Dell Inspiron mini 10) that I recently upgraded to an SSD (Plextor PX-256M3). The netbook has 1 GB of RAM (non-upgradable), and just the simple "Standard Dual Channel PCI IDE controller" - AHCI is not available.
It is speedy - sometimes. But it freezes up for about 11 seconds at a time occasionally during I/O. "Highest Active Time" will jump to 100% but without any (appreciable) disk transfer. The mouse will still move (usually), but essentially nothing happens (so I'll click something on the start menu, with no effect. The start menu is still open. A few seconds later it will come back to life and do what I asked). The disk section of "Resource Monitor" will show a response time of about 10-11 seconds (usually there will be a bunch; in this screenshot only one).
This happens every few seconds if I have something running in the background (A/V, Live Mesh), otherwise usually only in response to events (new tab in IE, etc) otherwise. So it is pretty much a crippling problem.
I understand the early SSDs (especially with JMicron controllers) were terrible at this (and Sandforce is finicky as well, from what I gather), but this is brand new and AFAIK has a Marvel controller.
Additionally, if I shut down the netbook, and transplant the disk (i.e. still same installation of Windows) into my laptop (Latitude D630), it runs swimmingly, even when the laptop is in IDE mode and not AHCI. So it's not the disk, it's not GC, lack of TRIM, or lack of NCQ (as far as I know, TRIM and NCQ require AHCI, right? So since it runs fine in my laptop in IDE mode it isn't them). I updated the firmware, that didn't help either.
The previous hard drive (5400 RPM) did not have this problem. It was just slow, as you'd expect. Even that never had ten-second I/O response times, it's just that it averaged a hundred milliseconds instead of zero.
I've tried disabling "shut down hard drive after.." in power management as well, also to no avail. Intel RST isn't installed - again, it's just "Standard Dual Channel PCI IDE Controller" with no evident ability to change that.