Member Avatar for grabbag

I see AGP video cards identified as X 4, X 8 etc; Let's say you buy a motherboard with an AGP Slot, which is common at the moment.

So what does all this mean?

Does this mean that an AGP video card rated X 2, or X 4, X 8 will only work or work properly with certain motherboards and not others?

What then are you looking for in NEW motherboards?

  • 3 Contributors
  • 2 Replies
  • 110 Views
  • 4 Days Discussion Span
  • Latest Post Latest Post by vicec64

Dani AI

Generated

Quick summary for : the "x" (1x, 2x, 4x, 8x) is how many data transfers happen per 66 MHz clock on the 32-bit AGP link. That gives approximate peak bandwidths of about 266 MB/s (1x), 533 MB/s (2x), 1.07 GB/s (4x) and 2.1 GB/s (8x). The card and the motherboard negotiate the highest mode they both support.

Compatibility is determined more by signalling voltage and physical keying than by the raw "x" number alone. Historical AGP revisions used different voltages: AGP 1.0 = 3.3V (1x/2x), AGP 2.0 = 1.5V (adds 4x), AGP 3.0 = 0.8V (adds 8x). If a board or card is "3.3V only" or "1.5V only" they may not fit or will not work; many later cards and boards are "universal" (have both notches) and will auto-negotiate. As pointed out, voltage is the usual gotcha.

Practical checklist:

  • Check the motherboard manual for the AGP voltage(s) and the maximum AGP mode supported.
  • Check the card labeling/box/PCB for "3.3V only", "1.5V only", "universal", or "AGP 4x/8x".
  • Inspect keying (notches); do not force a card into a mismatched slot.
  • If a card fails to boot, try forcing a lower AGP mode in BIOS (Auto, 4x, 2x, 1x) or update the BIOS/drivers.
  • Remember AGP Pro cards use a longer connector and extra power — they need a matching Pro slot.

As suggested, read the specs for background, but rely on the motherboard and card docs for real compatibility. AGP has largely been replaced by PCI Express x16 on modern motherboards, so prefer PCIe for new systems.

Recommended Answers

All 2 Replies

Member Avatar for DavidRyan

Wikipedia's AGP article has your answers.

Don't you love Wikipedia?

Member Avatar for vicec64

Regardless of AGP spec (2-4-8) being able to run a card on a mainboard has to do with the actual AGP voltage specification of the mainboard itself. Older mainboards will not run newer AGP spec'ed cards sometimes. Same with new mainboards with old AGP cards, but usualy the older card will work in any new mainboard (usually).

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.