Generally, Samsung is worse than Hynix, when it comes to graphics memory of that era.

I have a Prolink Ti 4200 64MB AGPx8 card. It has Samsung K4D64163HF-TC40 memory. Card can overclock from standard 250/500 up to 285/570.

Based on my experience, the AGP 4x versions are much better overclockers compared to the AGP 8X versions.
Also, 64 MB versions are more likely to have faster 3.6ns VRAM compared to 128 MB versions.

My favorite are the MSI GeForce 4 Ti 4200 64 MB cards (similar to the one in the attached photo). I have quite a few, and I've flashed two of them to almost Ti 4600 speeds (Core: 300 MHz / Memory: 640 MHz). They both run cool & stable (with custom cooling).

That's the exact model I have. It's the one I made a repair thread about recently.

NVIDIA GeForce 4 Ti 4200 triage and repair

Can you confirm if the memory chips on yours match mine?

Kahenraz wrote on 2021-12-24, 09:36:

That's the exact model I have. It's the one I made a repair thread about recently.

NVIDIA GeForce 4 Ti 4200 triage and repair

Can you confirm if the memory chips on yours match mine?

It is the same card, but with different memory.
My cards have VRAM from Hynix, rated at 3.6ns. Yours are from Samsung, rated at 4ns.
During that time, Hynix was better than Samsung, especially when it came to overclocking potential.

Attached photos with two of my cards before the cooling mod.