Log off at night. It will activate GC.

.....and stop doing 'speed/performance' tests. You should have a 'feel' for the speed of your own computer. If it's running right, leave it the fuck be. 

Yeah, like that's going to happen......right after I win the lottery.

I shut down at night. So, log off and leave it running?

I know the older OCZ ssd's had lots of complaints of failures, that's why I was kind of nervous about getting the Vertex 4, but with a 5 year warranty it looked like they were finally backing the product with some level of confidence. The Vertex 4 is insane in terms of speed. Like yrag said, I only had to use it to know it was insane in terms of speed. 

Log out and leave the computer on the login screen for a few hours a week. That's the best way to ensure GC is working. There is no way to turn it on and there is no way to turn it off. You can't check to see if it's working apart from monitoring performance (which just reverses any improvement by hammering the drive with random writes). There is simply no reason why it won't work as long as you give the drive time. GC is done at the SSD controller level, and is entirely independent of and invisible to the OS and other hardware.

While talking to Crucial about there garbage collection software for their SSD's, they told me to just either sign-off or log off your computer. Your computer will go in a rest state and the hard drives will shut down. The software will not work if there is any hard drive activity. This is when garbage collection starts working. They said to do it for at least 30 minutes, once a week, but the more the better depending on how much you’re writing to your drives on a daily basis.

Just for your general info.

ADATA: read 555 MB/s write 530 MB/s
IOPS: max. 90.000 (4K Random Write) 
Price :  179,90 EUR 3 year warranty

I dont know but with 5 euros difference i would go for the fast one, why do i write this just to know why people are so into OCZ they barely get sold here as far as iam told ( Shop ). I know OCZ sold pretty well when SSD´s came to the market and OCZ was marketing their products at conventions. 

 
 

I bought OCZ for price reasons, they were on sale...lol.

My laptop has a Samsung 840 series. I like it.

Did you scan virus? Some viruses make the hard drive slow down.

Garbage collection isn't changing anything. I see no difference at all.

I still don't understand the difference being half.

Yes, it's still faster than a platter, but from 408 to 200 seems like quite a loss to me.

Did you solve the problem ?
 

no.

For some strange reason i had the same problem today on a buddys computer... he is running windows 8 dont know if thats the case for your rig aswell ( and im not entirely sure it has to do with it )
i upgraded the bios... ( gigabyte motherboard ) seems that there is an issue with certain bios releases...
found this... http://forums.anandtech.com/archive/index.php/t-2192825.html

after i turned back to the previous bios update things still were not working had strange readings from the crystalmark aswell so i looked at the next thing energy settings ( windows )
I normaly make sure after i installed everything that the energy level is set to full throttle ( max power )
turns out that after the windows update these settings had been set to Energy save... turned it up again restarted and ran another test and well things are back to normal...

SO im not sure if it was the bios update or the windows update itself... you could try and set the energy level to max if that doesnt change there is a small percentage that the bios version if you updated is the cause... But before that try the energy settings in windows
Personally i never do a bios upgrade on my boards when things run as they should but my buddy wanted it all updated... Thats the reason i did it...if it was running on the same bios version before there is no need to worry about an upgrade... but if you did you might wanna go back but test windows settings first

Will read back later to see if this helps you or not...