Mac Pro 2009 upgrade

Been on a hackintosh since 2010 on clover and now on ozmozis.
I am not a noob or advenced user, something in a middle, so I always have a problems with hardware tuning in hackintosh.
I dicided to sell some parts of hackintosh. It was GA-Z97X gaming 7 motherboard and I7-4770 processor.I left wifi/bluetooth card bcm94360cd with PCI-E adapter with antenas. Two 8gb crucial ballistix sport memory cards, so together 16 gb (they 1600MHz)
After researching, a week ago i bought Mac Pro 4.1 year 2009 from UK. It cost Me about 530 Euros with postage.
I was looking only for Mac pro 4.1 and 5.1 and only with two processor slots due to the capability of upgrade in the future.
Mac 4.1 on the fifth part is cheaper then 5.1, and Mac 4.1 can be firmware updated to 5.1 due to the same hardware inside it.
Specification are:
Mac Pro (Early 2009) 4.1
8-core: Two 2.66GHz Quad-Core Intel Xeon 5500 processors
Memory: 4gb
NVIDIA GeForce GT 120 with 512MB of GDDR3 memory
HDD: 500GB with El Capitan

Upgrade will be updated soon!

You get good machine for very cheap
I am thinking later on to upgrade to 2 x X5690 six cores and add ram in sum of 64, not more.
Than I have deal for 3gb r9 280x video card for 80 euros
Here is a picture of My rig
I have aded 16gb of ram
And I bought from 1deins.de 256GB Samsung SSD SM961 M.2 and from e-bay PCI-E 4X for M.2 SSD ADAPTER radiator version (pictures attached) but PCI-e SM961 not works like bootable drive with Mac Pro in High Sierra (only external drive speed approximately 1450 read and write), but I think you can do that with hackintosh and real pc but not with Mac Pro due to the efi
So now I am selling it and want to by AHCI ssd drive sm951 for my Mac Pro
Mac Pro have only max PCI Express 2.0 so you can get faster than 1500 read and write speed due to old interface
geekbench benchmarks attached

I posted back to shop bought SM961 because it was working only like external hard drive. But I need ssd for booting OSX so now I looking for Samsung SM951 AHCI version it should work without any kexts and other stuff (natively)
When I was testing SM961 on Mac Pro the read and write speed was about 1450 and it is not going to be higher on SM951. After I buy ssd I will post benchmarks

Here it is:

As I said, I'm posting benchmarks of Samsung SM951 AHCI 256gb M2 2280 PCIe SSD which connected to the third PCI port with cooling version of adapter.
Running on a Mac natively (no kexts or patches applied) in APFS
Bought used about 110 euros with postage from ebay.
This ssd was removed from a Lenovo ThinkPad X1 Carbon (Gen 3)
Part number: MZHPV256HDGL-000L1
If you buy Samsung version with part number MZHPV256HDGL-00000 then i think you get read/write speed of 1400 MB/s

8-core: Two 2.66GHz Quad-Core Intel Xeon 5500 processors upgrade to 12-core: Two 3.33GHz Quad-Core Intel Xeon 5680 processors
IHS removed