How full was the drive at each instance?

That info is in the screenshots. 

Now: 39% of 238 GB.

Then:  23% of 238 GB.

It will be interesting to hear, after you contact the maker of the SSD, as to what may have caused the difference in the write speeds. 

Jim, I think your answer is going to be here:  http://www.anandtech.com/print/5817

and has to do with incompressible data write rates.

Here:  http://forums.anandtech.com/showthread.php?t=2281922

Anand's own testing showed rates comparable to what you're seeing, so I don't think you actually have a problem.

But half?

What's the point then?

Sharpen your crayon.

part of the problem is OCZ drives are of very poor quality compared to much of what else is availabl despite all of the raving over them across tech. sites

sustained random write iops is the single most important metric across the board; try comparing a Mushkin "enhanced chronos" or current-generation Corsair drive off NewEgg or elsewhere to the current and recent-history generations of OCZ consumer drives...   there's a reason their company almost went under!

have you checked to see if any firmware updates are available?   ...did your benchmarking software get updated and begin disabling trim temporarily (or hopefully not permanently) for "testing purposes" ?

p.s; had a bit of trouble following this thread but did you say that you installed a new video card..? that may have had something to do with it - if you don't manually set your pagefile size windows would have automatically increased the initial paging filesize on your default page drive (boot drive, which I'm assuming is your ssd) while also increasing the reserved freespace for its expansion and copying any data from the front of the address-space to make room - that can be a taxing operation especially if your ssd had an abundance of temporary or unmovable files or/and pending updates around the time the operation occured

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. 

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

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.

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

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