SSD fast reads, REALLY slow writes

I upgraded my PC about six months ago. I installed a Plextor PX-128M6Pro for Win7 and Program Files. I've got spinning drives for just about everything else. My old SSD is an 80Gb Corsair (Device Manager shows it as a SandForce[290900]). I left that in the system to use when I wanted good performance on particular applications/games. So today I decided to start using it, and I've discovered that I'm getting incredibly slow writes to the drive.

When I say I'm getting slow writes, I mean creating a shortcut for a file on the drive took 55 seconds. Right-clicking in a directory to create a new directory took a minute and 10 seconds for the new directory to show up. I then named it, and when I hit the <Enter> key to save the new name, it took a minute.

I can navigate the drive without any slowdowns, and I can copy files from the drive to other drives without any problems. None of my other drives are doing this.

Any suggestions what could be causing this?

Motherboard: Gigabyte Z97X Gaming 7 (all drivers up to date)
Windows 7 Home Premium, SP1, 64-bit

So not every write is slow. About 10% of them go fine.

It is now.

After I did that, it seemed better. I created a directory and deleted it without any problems. I rebooted and the drive wasn't showing in Explorer or in Disk Management. I rebooted again, and it was there, but it was slow like before.

I'm starting to think the drive is going bad.

I may have figured out the problem. I replaced the SATA cable, and so far, I haven't had any slowdowns with some preliminary tests. I will update after more testing.

Yup. It was definitely the cable. My machine is running smooth as hell now. Thanks for the help all.