3090 on old hardware sounds like bottleneck hell.

Use the black friday sales to upgrade your Motherboard, Ram, CPU, and PSU.

The problem with 4060ti on an old hardware is that it runs using only 8x PCIe lanes, and it shows on even PCIe gen3. And your I5 2500 uses even older PCIe gen2. For LLMs, if you only going to use 7B, which might fit entirely on 16GB VRAM, it should be kinda OK. But for everything else you are going to have a very bad time.

I would go with rtx 3090. You can always upgrade the rest once you get budget or needs in the future. I don’t think you should be bottlenecked by PCI Express. I had my rtx 3090 ti running in pcie 4.0 4x before I figured out there was some issue and I was getting good performance with exllama 2.4bpw llama 70B and other models that fit in VRAM. Training with QLoRA worked just fine too. That’s basically what you will get with pcie 2.0 x 16. I don’t know why it doesn’t want to kick in into 16x for me, but I was able to get it working with x8 by physically putting it in again, but I don’t see much difference with AI stuff.

3090 for more VRAM = bigger models

Both are bad choices:

IDK about the 3090 and the PSU, that thing can spike HARD, in the 1.6KW range, and if you PSU is a lower end one, it will kill it. I head a lot of people on 120V countries complain because it actually cause their lights to flicker.

The 4060 Ti is limited by PCI-E 8X at 2.0 speeds, but that is a XX50 chip masquerading as a 60, so it sips power.

3090 would be better, but you dont have the PC for it. Get a cheap used AMD B550 board for PCI-E 4.0, 64 GB of RAM and whatever CPU is within your remaining budget, all the way down from R5 3600 to R7 5800X3D, AM4 is really well segmented for price, even new. You will get better gaming performance too, and can run a lot of stuff in CPU with 64 GB of RAM.

Try selling everything (the pc and spare PSU) and consider buying a decent used platform with AVX2 and a 1000w+ PSU, then see what GPU you can still afford. Plus, if you are just toying llms without training them, P40s are options too, if you can get one for around 100 Euro.

I went 4060ti 16gb on small black Friday sale because I don’t want to upgrade my PSU, and it’s my workstation for both my jobs so I don’t want to mess with a used or refurbished 3090 which would be a lot more money if I factor the PSU.

This way it costs me less than half as much for new gear and my goals is to just run 20b, 13b and smaller coding models and in time I feel like something with higher vram will come out at a reasonable price without requiring a huge PSU.

I also have 64 gigs of ram if I need to call on a larger model.