I think that AGP Voodoo cards are good for overclocking on the AGP bus.

My Voodoo5 stops reliably going into 3D before 90 MHz. 2D is fine but when I start a game it will usually freeze the whole sys.

Maybe Voodoo3? But I'm not sure that there is any card that is truly reliable at that speed.

This is why the PCI Voodoo3/4/5 cards are sought after.

I have successfully used several GeForce 1 through 4 cards in BX motherboards with AGP @ 89 MHz for years without a single issue in 3D games. Actually the only problem I ever found was that my P3B-F is prone to hang in some 2D fullscreen games when it is filled with 4x256 Mb of RAM. You must disable SBA either in BIOS or NVstrap driver in order to keep the system completely stable.

batracio wrote:

I have successfully used several GeForce 1 through 4 cards in BX motherboards with AGP @ 89 MHz for years without a single issue in 3D games. Actually the only problem I ever found was that my P3B-F is prone to hang in some 2D fullscreen games when it is filled with 4x256 Mb of RAM. You must disable SBA either in BIOS or NVstrap driver in order to keep the system completely stable.

Just an idea:
Could it be that AGP 4x cards have, in theory, less problems with an overclocked AGP 2x bus since those cards are made to be able to run at 4x throughput anyway?
It would explain why Voodoo's seem to have more problems running on averclocked AGP 2x ports then contemporary NV cards.

I've had problems with GeForces.

Overclocked AGP success is surely a combination of motherboard, chipset and video card quality. I would also imagine that it will vary between chips like overclocking tolerances of CPUs vary.

AGP 4x is still 66 MHz but it uses multiple transactions per clock tick. It's quad data rate like Intel's FSB. They are also lower voltage when at 4x. I don't know if they would be inherently better at 3.3v. You'd need to ask somebody who designs this stuff probably.