Help with cuda compatibility on ancient mobo

Hello all, I have spent a week scouring the interwebs trying to find the answer to an issue I have with an old pc I built back in 2008-09.
The specs are below, but in a nutshell I have a asus dx58S0 mobo, with first gen i7 cuadcore processor
I have installed new ram, 16gb limit, ddr3 1600 pc3l 12800/ pc3 12800 non ecc unbuffoered 1,35v
I am not sure in which forum to post this, developers or gamers, I chose developers because many of you are using the GPU in innovative ways and therefor you are far better acquainted with CUDA and driver development/compatibility
I cloned hdd to sdd to speed up transfer times and extend OS (I have zero partitions, all OS installed on individual drives, boot handled by grub) on one I have XP with old softimage xsi and other programs installed which are still part of my production pipeline to this day.
I cleaned everything and installed win 10 and stripped it down where I have 1% cpu and 3% ram usage at idle, it´s the best I could do.
I have dual nvidia geforce gts 250 sli config, on win 10 the driver works, sli works, but unfortunately I am trying to turn this pc into a vfx 3d workstation for my nephewwho wants to make cartoons and animation. I myself worked lots of 3d graphic design and web development over the years, and I know I can install adobe cs5 and blender (current)on the machine, but the issues are with davvinci resolve, where it throws a procedure error on launch, after research I found I need cuda archetecture greater than 11.1,
I know hopper archetecture is cuda 12 but it forces be to stay with new nvidia cards, even the refurbished ones are insane pricing wise.
here’s my question, and I have looked believe me, so please no “rtfm!” type of questions, I have ptsd from Linux forums in the early 2000’s :P
I need to find an nvida card, new or refurbished, which has the juice to run the best games today(even on lowest settings is acceptable) but more importantly meet the gpu requirements of blender, houdini, davinci resolve and nuke, so I need cuda 11.1 or greater, perhaps the previous gen´s archetecture driver provides cuda higher than that or if anyone knows the best current moedel which is the perfect midway between highend and the bare minimal, that would be a welcomed suggestion as well.
EDIT: i have found the cuda 11.1 release notes, so I know the general timeline of release, but I know there are many of you are GPU masters and have seen it all, so I still need your invaluable opinion on this matter since there are things you may take into consideration which I may not.
The old pc has juice, it can play all sorts of games well and it handles bleder and renders qucikly but the other software are requiring CUDA 11.1 or greater to launch.
I am aware that my PCIe slots are 2.0 and there will be transfer lag if the new card is 3.0-6.0 Im hopiong someone might find a card which meets the cuda requirements but is maybe for pcIe 4…I beleive cards built for PCIe3.0 were manufactured PRIOR to the architecture.

please forgive any typos or misspellings, typing this on a text editor.

OS Name Microsoft Windows 10 Home
Version 10.0.19042 Build 19042
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name
System Manufacturer
System Model
System Type x64-based PC
System SKU
Processor Intel(R) Core™ i7 CPU 920 @ 2.67GHz, 2661 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date Intel Corp. SOX5810J.86A.4014.2009.0507.1930, 5/7/2009
SMBIOS Version 2.5
Embedded Controller Version 0.00
BIOS Mode Legacy (has UEFI option to enable at boot)
BaseBoard Manufacturer Intel Corporation
BaseBoard Product DX58SO
BaseBoard Version AAE29331-503
Platform Role Workstation
Secure Boot State Unsupported
PCR7 Configuration Binding Not Possible
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = “10.0.19041.2728”
User Name
Time Zone
Installed Physical Memory (RAM) 16.0 GB
Total Physical Memory 16.0 GB
Available Physical Memory 12.1 GB
Total Virtual Memory 18.9 GB
Available Virtual Memory 14.6 GB
Page File Space 2.88 GB
Page File C:\pagefile.sys
Kernel DMA Protection Off
Virtualization-based security Not enabled
Device Encryption Support Reasons for failed automatic device encryption: TPM is not usable, PCR7 binding is not supported, Hardware Security Test Interface failed and device is not Modern Standby, Un-allowed DMA capable bus/device(s) detected, TPM is not usable
Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualization Enabled in Firmware No
Hyper-V - Data Execution Protection Yes

Your GTS 250’s ceased to be supported beyond Cuda 6.5, hence not being of use now.

With a Cuda 11.1 minimum, the oldest generation card applicable would be Kepler 3.5 based cards with at least 4GB of VRAM, which Resolve requires, but how well they would meet your requirement:

I’m not sure.

If you haven’t already seen it, this page may give you some pointers.