Weird freezing problem?

Okay, so for about a month now I've been having a weird problem. I'm 90% sure I need to replace something but I don't know what. Here's what happens: I turn on my computer, things are pretty slow. For the first 20-or-so minutes, programs freeze and hang a lot. This isn't such a big deal, but at random times, if I open a folder or open/close a tab in Chrome, the whole computer freezes for about 5-10 seconds. This problem will last for about 30 minutes then things will be fine, and it can just start happening again at random times throughout the day. For example, starting a recording in Fraps often restarts the problem. I've asked a lot of people about this and I've never gotten a definite answer, but someone suggested it might be the PSU. Also note I'm terrible with computers so if anyone decides to help me out, have fun.

Specs (since the first thing people do is ask for them when I tell them about this):
OS Name Microsoft Windows 7 Home Premium
Version 6.1.7601 Service Pack 1 Build 7601
OS Manufacturer Microsoft Corporation
System Model Lenovo H430
System Type x64-based PC
Processor Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz, 3401 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date LENOVO ECKT16A, 06/04/2012
SMBIOS Version 2.7
Memory: 8192MB RAM

Drive C:
Description Local Fixed Disk
Compressed No
File System NTFS
Size 1.79 TB (1,973,369,696,256 bytes)
Free Space 568.00 GB (609,888,559,104 bytes)
Volume Name
Volume Serial Number 4A427869

Drive D:
Description CD-ROM Disc

Drive F:
Description Local Fixed Disk
Compressed No
File System NTFS
Size 1.82 TB (2,000,396,742,656 bytes)
Free Space 1.52 TB (1,670,761,500,672 bytes)
Volume Name Secondary
Volume Serial Number 68FFCC70

Sorry, I probably should've mentioned this first also, I'm not sure if it makes a difference but every hour or so I can hear my secondary hard drive shut down then hear the sound of it starting up again whenever I open a file on it. I'm not sure if this changes anything, so I'll still run Memtest just in case. This didn't start happening until I was having the freezing problem I mentioned but I'm not sure if they're related at all.

TheGuyWithAHat said:

Wait, your second hard-drive shuts down?

Which hard-drive has your Windows Installation on it?

The only files on my second hard drive are some recordings, that's all I use it for.

Doing Memtest86+ at the moment, will switch the sata cables afterwards if I get no errors. Also, about how many passes do you think is enough for each stick? The first stick has done 12 passes so far with no errors.

Ran a 24+ hour test on each stick, no errors found. Bleh.

Tested with Parkdale, these were my results

Primary: ST2000DM - 001-9YN164 - CC62
Seq. Write Speed: 171.5 MByte/sec
Random QD32: 1289.3 kByte/sec, 322.3 OPS, 3.10 ms

Seq. Read Speed: 168.5 MByte/sec
Random QD32: 598.6 kByte/sec, 149.6 IOPS, 6.68 ms

Secondary: ST2000DM - 001-1CH164 - CC24
Seq. Write Speed: 171.4 MByte/sec
Random QD32: 1552.0 kByte/sec, 388.0 IOPS, 2.58 ms

Seq. Read Speed: 185.9 MByte/sec
Random QD32: 633.2 kByte/sec, 158.3 IOPS, 6.32 ms