A GeForce 4 Ti 4600 that powers on but never clears POST — fans spin, no beep, black screen — is almost always an AGP signaling problem, not a dead card. The Ti 4600 (NV25) is a 1.5 V AGP 4x card, and pairing it with a 3.3 V AGP 1.0 motherboard is the single most common reason a clean card refuses to boot. This guide walks the diagnosis in the order that actually finds the fault fastest, from voltage keying to BIOS to power.
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The most common cause: AGP voltage keying
The Ti 4600 expects 1.5 V AGP signaling and is keyed accordingly. Many late-'90s boards — including most Intel 440BX builds — drive the AGP slot at 3.3 V (AGP 1.0). A universal slot accepts both, but a 3.3 V-only slot will either refuse a 1.5 V card physically or, worse, sit there not POSTing if the keying is marginal. This is why the Ti 4600 belongs in a Pentium 4 / Socket 478 build on an 845 or 865 chipset, where the AGP slot is 1.5 V AGP 4x native. If you're trying to run one on a 440BX Pentium III board, voltage mismatch is your prime suspect — confirm your board's AGP spec before chasing anything else.
Diagnostic flow
Work these in order; stop when the display comes up.
- Confirm slot voltage. Check the motherboard manual or the slot key position. A 3.3 V-only AGP 1.0 slot is incompatible with the 1.5 V Ti 4600. If that's your board, the card was never going to POST — move it to a 1.5 V-capable board.
- Reseat and inspect. Pull the card, check for bent or corroded AGP fingers, and reseat firmly until the retention clip engages. Oxidized contacts are a classic no-display cause on 20-year-old cards — clean the edge connector with isopropyl alcohol.
- Check the AGP retention bracket. The Ti 4600 is a heavy card; if it isn't fully latched, it can lift a few thousandths and lose contact under its own weight. Make sure the rear bracket is screwed down and the slot clip is locked.
- Verify the PSU rails. A tired period PSU sagging on the 3.3 V or 5 V rail will boot a light card but choke on a power-hungry Ti 4600. Test with a known-good modern unit with the right connectors before assuming the GPU is dead.
- Update the motherboard BIOS. Some early boards need a BIOS update to recognize newer AGP cards and to set the AGP aperture correctly. Flash to the latest revision for your board and set the AGP aperture to 128 MB or 256 MB.
- Clear CMOS. A stale CMOS with a conflicting AGP setting can block POST. Clear it, let the board redetect, and retry.
If it POSTs but Windows shows no display
A card that POSTs (you see the BIOS splash) but goes black entering Windows is a driver problem, not hardware. Boot to Safe Mode, remove any ghost display adapters in Device Manager, and install the correct period driver — the final NVIDIA Detonator/ForceWare set for the Ti series under your OS. Resist the urge to use the newest driver; period-appropriate drivers are more stable on these boards.
When it really is the card
If you've confirmed a 1.5 V slot, good power, a fresh BIOS, and clean contacts and it still won't POST, the failure modes that remain are a cracked GPU solder joint (common after decades of thermal cycling), failed VRAM, or a dead RAMDAC. A reflow can revive a cold joint, but at that point a tested replacement is usually the better value than chasing a board-level repair.
AGP keying, in plain terms
AGP slots and cards use physical notches to enforce voltage compatibility, and understanding them sidesteps the no-POST trap entirely. There are three relevant types. A 3.3 V slot (AGP 1.0) has its key toward the I/O bracket. A 1.5 V slot (AGP 2.0/3.0) has its key toward the rear of the board. A universal slot has no key and accepts both. The GeForce 4 Ti 4600 is a 1.5 V card: a 3.3 V-only slot is physically keyed to reject it, a universal slot accepts it, and a board that is electrically 3.3 V but universally keyed will let the card seat yet may never POST because the signaling is wrong.
This is the heart of the 440BX problem. Many BX boards expose a universal or 3.3 V AGP slot running AGP 2x at 3.3 V signaling. The Ti 4600 often physically fits but behaves unreliably or refuses to initialize. A few late BX revisions with the right AGP bridge cope; many don't. If period-correctness allows, the clean answer is to put the Ti 4600 where it belongs — a Socket 478 Pentium 4 board with native 1.5 V AGP 4x.
Confirm the model, too. The GeForce 4 Ti (NV25) and the GeForce 4 MX (NV17/18) are different silicon with different power and AGP behavior. If your card is actually an MX, the diagnosis shifts — verify the exact model with GPU-Z on a working system or by the board markings before chasing voltage.
Bench tools that speed this up
A multimeter to confirm PSU rails under load, compressed air and isopropyl alcohol for the edge connector, a spare known-good PSU, and a second 1.5 V-capable AGP board for swap testing will resolve nearly every case faster than trial-and-error driver installs. A POST diagnostic card is a luxury, but it pinpoints exactly where initialization stalls — invaluable when the screen never lights at all.
Frequently asked questions
Why won't my GeForce 4 Ti 4600 work in my Pentium III 440BX build? Because most 440BX boards drive AGP at 3.3 V (AGP 1.0) and the Ti 4600 is a 1.5 V AGP 4x card. The voltage mismatch is the usual no-POST cause. The Ti 4600 belongs in a 1.5 V AGP 4x board, typically a Pentium 4 845/865 system.
The fans spin but there's no beep or display — is the card dead? Not necessarily. Spinning fans only confirm power, not initialization. Work the diagnostic flow above — voltage keying, reseating, PSU, and BIOS account for most no-display cases before the card itself is at fault.
What's the period-correct platform for a Ti 4600? A Socket 478 Pentium 4 Northwood on an 845 or 865 chipset, which provides native 1.5 V AGP 4x.
