So i had my system up and running perfect, i just bought my SSD today and had a 7.9 WEI. Then i copied my wow folder from my HDD to SSD and something went wrong, something was continually filling my SSD up with data, to the point of "warning low disk space" messages. Let me make this clear, WoW did not fill it up, i had 18gb's left after i coiped the folder, something else happened and i have no idea what. So then i do a reformat because i had no idea what was taking up the space.
Now im back with everything set up perfect, trim is working as i verified it with CMD tool, i have my page file moved to my HDD, i have hibernation turned off and yet, my WEI dropped to 7.2. And the drive is even performing slower, confirmed by ATTO disk benchmark software, my 4k reads and writes are much lower, but i do get advertised speeds at the higher numbers.
What the hell could have happened? Trims working just fine.
When you fill up a SSD, there will be no available nand blocks with which to do an update with a simple write, and a read/rewrite will need to be done. Trim makes nand blocks available when a delete is done without requiring a read/rewrite. If you need to do an update, and no free nand blocks are available, it will take longer, even with trim.
Exactly which SSD do you have?
Different models will have different methods of reclaiming free nand blocks through background garbage collection.
A secure erase will reset all of the nand blocks to a free and available state.
Different vendors will have utilities that can accelerate the freeing of unneeded blocks. For Intel, look for the Intel SSD toolbox.
If you will be running with only 18% free space, you might consider moving some more stuff off of the ssd.
I have a OCZ Agility 3 (rated at up to 550MB/s) hooked up to the SATA III port on my P8Z68-V PRO GEN 3 Motherboard (via SATA 6.0 cable, of course) and from a fresh install of Windows 8, the WEI gave me a score of 7.9. After installing many programs and filling up about 80% of the SSD, I reran the test and I get 7.6 or 7.7. I ran several ATTO tests and the drive hits its peak read/write speed after 1024kb. Before that point, theres kind of a sliding scale where the read/write speeds are really low at 4kb then start to increase as the transfer size increases. I think this is the reason that the packaging for the SSD only shows its peak read/write speed and not the low end. I'm sure there are better SSDs that have much better random or low KB read/write speeds and I think that the WEI is averaging the speeds or something. Also, having more data on the SSD seems to slow down the WEI score even though the ATTO benches are identical regardless of available space on the drive. So basically what I'm trying to say is don't let the WEI get you down, as long as your drive passes ATTO or other benches. Hope this helps...