I'm working on a Dell Vostro desktop circa 2011 with Windows 7 Pro 64, 2GB RAM.
The system was working *VERY* slowly but was working.
I cleaned it up re: parasites or PUPs which I'm sure was a help but no fix.
I see no behavior that would indicate parasites remaining - although I could take more drastic steps in this regard.
[As background, I have seen on rare occasion hard drives that would test "OK" yet had a VERY low data transfer rate. Cloning them and replacing with a new hard drive fixed the problem.]
I tested the computer with HDTune and found the data transfer rate to be below 3MB/s average.
Of course, this is at least 20 time slower than "normal".
I replaced the hard drive but it didn't help so I put the original back.
I updated the BIOS and updated the chipset drivers.
Altogether these things seemed to help.
Now the computer works fine some of the time and it reverts to sluggish performance at other times.
HDTune tests confirm that the data rate is either "normal" at around 85MB/s average or abnormal at below 3MB/s average. I have seen the performance switch in the middle of an HDTune test!
I'm looking for ideas as it seems to not be likely to be a lurking parasite. Not likely chipset drivers. Not likely BIOS-related (the new BIOS has almost no settings beyond boot order and power options). I've not replaced the SATA cable but I did switch the SATA port on the mainboard.
What might you suggest as likely things to pursue?