My thoughts on this are that the PCI slot is going to be a performance bottleneck to faster than your already getting from your SATA II controller. PCI Express might be able to get past the bandwidth bottleneck, but I have serious doubts if older PCI slot adapter will out perform a SATA II controller direct on board connected to the main faster BUS.
I am actually surprised that you said that the older 256GB SSD is slow. I myself have some early SSD's in the 60 to 120GB capacity and they all run fast connected directly to SATA II onboard. While they might not be fast in comparison to newer SSD's, the OS boots to desktop in under 20 seconds after Windows splash logo and thats much faster than systems with HDD.
Are you using this for something where there are excessive read/write processes where a faster SSD is really needed or is it just the need for speed knowing there is faster and that bothers you so you want faster?
I had an application where I needed as fast of Read/Writing as I could get for a project that built upon prior written information. It hammered a HDD hard and so i tried it with a SSD. SSD was much faster, then I read up on a RAMDrive where you can allocate a section of system RAM to act as a Drive. So I allocated 2GB of 8GB DDR3 1600Mhz and HOLY CRAP was that FAST!!!!!!!!! Benchmarked the "Virtual" Drive acting in system RAM and it was 22x faster than my fastest Crucial M500 240GB SATA III SSD in SATA II connection.
RAM Drives basically are created by you using software/ Then that software creates an image of the RAM Drive and stores that image in on a HDD or SSD. Upon shutdown it writes whatever changes happened between boot and shutdown to the image file. And upon boot it injects that image back into the allocated space of system RAM. Depending on how much data is written from HDD or SSD to RAM on boot and written from RAM to HDD or SSD at shutdown affects the initial boot process speed. I have no problem turning a computer on and waiting 2 minutes for a 2GB RAMDrive to be ready as for while the system is running after that performance is insanely fast through that 2GB RAM Drive.
You can even put games on these RAMDrives and have the game run completely from system RAM so data is direct between the CPU and RAM. It doesnt get any faster than that!!!!
Unless you then start upgrading RAM or CPU for faster performance components.
https://en.wikipedia.org/wiki/RAM_drivehttps://www.pcworld.com/article/260918/how_to_supercharge_your_pc_with_a_ram_disk.htmlHere is the product i have used before:
http://memory.dataram.com/products-and-services/software/ramdisk*Note: Older versions allowed up to 2GB for free and they have since sized that down to 1GB for free. I guess there were too many people able to get by for free on 2GB without paying. Also there are other companies selling them too. Toshiba was selling a software solution for making RAMDisk/RAMDrive's geared towards gamers. Looks like AMD now is selling towards gamers as linked below. If you only have a need for a very fast 1GB space for a game or project there is the free solution of DataRAM RAMDisk. Additionally the 1GB DataRAM RAMDisk could be used for benchmarking to see how it would speed up your systems access to information before buying into a product for a larger capacity.
Up to 24GB Drive allocation of System RAM Gamer RAMDisk
https://www.amd.com/en-us/products/memory/ramdiskMaybe maxing out your RAM and use of a RAMDisk/RAMdrive is a solution for faster performance you need of a specific application or game. For me it was C++ code I wrote that passed data to a MySQL database and the system was reading and writing information from database and building upon it. It was Read/Write intensive which for a hard drive isnt that hard on the drive because HDD's are built for heavy read/write processes however it was SLOW with HDD light on constant and CPU utilization only 60% on a Athlon II x4 620 2.6Ghz CPU. I moved it over to my SSD and I burned out a OCZ 90GB SSD where I guess I reached the maximum cell writes and killed it. I knew using a SSD for this it was going to be fast, but also it was going to wear on the drive fast and well it did, I killed that SSD after 18 months of heavy use. CPU utilization of this process shot up to 92-100% so I knew that the CPU was no longer waiting for the hard drives lag to read/write, as the SSD was faster at sending and receiving info. I then discovered RAMDriving and how RAM is even more rugged than a HDD for massive read/write processes and FASTER!!! So I went this route for speed and not battering to death SSD's which have limited cell write cycles. This put my system at 100% CPU utilization which means its running full tilt ( = maximum efficiency and at full CPU/RAM performance ) and it was able to complete so much faster than the other methods.
