Introduction
The Intel 440LX chipset introduced the AGP-Slot for the first time. At that time graphic cards used the PCI bus for data transfer and there weren’t any special power considerations for the AGP-Slot. Nearly all designers used the PCI power recommendation for the AGP Slot as well, which was ok at that design stage and suited all available AGP VGA cards.
Problems With The AGP-Power Supply
With the arrival of the Nvidia TnT chip this AGP power design had reached its limit. Many LX-systems with TnT either crashed during games or they didn’t start at all. Some motherboard vendors modified the design for future revision of their 440LX motherboards, but most of them waited for the new 440BX design to implement a better AGP Slot power supply.
Solutions
There are a couple of ways to fix the power consumption problem. First, provide a better power supply to the AGP Slot or connect the 3.3 V of the AGP Slot directly to the ATX Power Connector.
Alternatively, the 3D-chip makers shrunk the graphics chip e.g. from .25u to .18u. When a chip structure gets smaller, the power consumption at the same clock speed is reduced too. Both ways were used to tackle the graphics power consumption problem. The shrink of the graphics chip not only allows you to reduce the consumed power, the heat of the chip and the voltage, but also enables you to get a higher frequency out of the same design.
This brought the AGP-card back to the vicious circle of high power consumption plus heat spreading. Higher frequencies, more on chip features (like T&L), more memory and more graphic chips require more power and produce more heat, which in turn requires more cooling.
AGP Pro
AGP Pro had been released in April 1999 to provide that necessary power and consequent cooling to a computer system. The AGP Pro Connector is fully backward compatible and offers additional pins at the front and the back of the connector.
Like the AGP slot, the AGP Pro slot comes in different versions, which are AGP Pro 3.3V, AGP Pro 1.5V and AGP Universal. The first two have blocking pins to prevent insertion of an unsupported AGP (Pro) card. All the motherboards with AGP Pro slot that we reviewed so far are using the AGP Pro Universal slot.
The current AGP slot can supply up to 25 W to the graphics card. With the two additional pins, PRSNT1# & PRSNT2# , the AGP Pro cards report its power requirements to the motherboard. An AGP Pro slot can provide a total of 50W or 110W.
Lots Of Power = Lots Of Heat
With so much huge power being consumed the card is naturally generating a lot of heat. Therefore, the AGP Pro graphics card will need the space of the neighbouring PCI slots for cooling. The AGP Pro50 (50W) card requires 1 adjacent unused PCI slot, and the AGP Pro110 (110W) Card requires up to 2 adjacent unused PCI slots.
Sample of an AGP Pro50 back panel of the Fire GL3 card
Final Thoughts
For the time being, mainstream graphic cards will remain normal AGP cards for several reasons, like cost and a graphics power budget below 25W. Workstation class or high performance motherboards will come with AGP Pro to gain market share in the prestigious high-end market, which will soon bring this beefed up AGP-slot to the mainstream motherboards as well. Finally, once AGP Pro motherboards become more widely available, those graphic cards might also follow into the mainstream market.
AGP Pro provides the steroids for graphic cards with more than 64MB of high speed VGA memory, higher graphic chip clock-rates and additional graphic chips. Like every steroid it is first seen in the high-end graphics market and will then filter down into the mainstream market.