Slow external ssd

[bstobbe]

Just hooked up a new vertex 4 external SSD via eSATA III. Seems to not be getting the speeds I would expect. I've seen a lot of things about TRIM and indexing and what not while researching SSD speed issues but I don't know how many of those tips actually apply when your SSD is external i.e. not hosting your OS so I haven't ventured into any of that yet. I want to make sure I'm not missing something more major here first. I'll attempt to provide all the specs, let me konw if I'm missing any useful information. I'd really like to get the most out of this setup.

mobo: GIGABYTE GA-EP35C-DS3R LGA 775 Intel P35 ATX Dynamic Energy Saver Ultra Durable II Intel Motherboard
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128082

internal drive with Windows 7: Western Digital Raptor WD1500ADFD 150GB 10000 RPM 16MB Cache SATA 1.5Gb/s 3.5" Hard Drive -Bare Drive
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136012

external SSD: OCZ Technology 256GB Vertex 4 Series SATA 6.0 GB/s 2.5-Inch Solid State Drive (SSD) With Industry's Highest 120K IOPS And 5-Year Warranty - VTX4-25SAT3-256G
http://www.amazon.com/OCZ-Technology-2-5-Inch-Industrys-Warranty/dp/B007RARHSO/ref=sr_1_1?ie=UTF8&qid=1355371789&sr=8-1&keywords=vertex+4

external enclosure: MiniPro 2.5-inch eSATA 6Gb/s, USB 3.0 External Hard Drive Enclosure (9.5mm, 12.5mm)
http://www.amazon.com/gp/product/B003XEZ33Y/ref=oh_details_o02_s00_i00

eSATA card: StarTech PEXESAT32 2 Port SATA 6 Gbps PCI Express eSATA Controller Card
http://www.amazon.com/gp/product/B003GSGMPU/ref=oh_details_o03_s00_i01

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My understanding is using a x1 PCI Express connection I should get 200MB/s yet I'm seeing around 120 only.
Since I originally posted I've disabled indexing, verified TRIM is enabled, verified write caching is enabled, verified AHCI is enabled, verified disk defrag is disabled, and verified drive compression is disabled. The other following suggestions I don't know if I can do JUST for the external SSD so I did not mess with them: use RAM cache, turn off superfetch & prefetch, and place page file on SSD.
One other piece of info, my eSATA controller card installed Marvell 91xx after I put it in.
If anyone has any idea why I'm not getting 200MB/s write speed, let me know.

 

[bstobbe]

I think I may have found the "something major" issue I suspected I might be experiencing... After installing HWiNFO64 I determined that my PCI Express x1 slots are only version 1.0 which has amaximum of 250MB/s. Lame! I guess the only question now is whether or not 192MB/s read, 119MB/s write is the best I should expect given the circumstances. If so... ugh, might have to start looking at new motherboards.