slot 1x e 4x non dovrebbero essere alimentate dalla mobo, ma mi riservo di verificare.
Sono tutti alimentati, solo che 1x16 hanno solo 25 W contro i 75w dei 16x16
Per questo e' necessario alimentare i riser 1x16 , perche' e' quasi sicuro che chi progetta la GPU 16x, si aspetti 75 w dal bus e non 25 W
http://en.wikipedia.org/wiki/PCI_ExpressPower
All sizes of ×4 and ×8 PCI Express cards are allowed a maximum power consumption of 25 W.
All ×1 cards are initially 10 W; full-height cards may configure themselves as 'high-power' to reach 25 W, while half-height ×1 cards are fixed at 10 W.
All sizes of ×16 cards are initially 25 W; like ×1 cards, half-height cards are limited to this number while full-height cards may increase their power after configuration.
They can use up to 75 W (3.3 V/3 A + 12 V/5.5 A), though the specification demands that the higher-power configuration be used for graphics cards only, while cards of other purposes are to remain at 25 W.[9][10] Optional connectors add 75 W (6-pin) and/or 150 W (8-pin) power for up to 300 W total (2×75 W + 1×150 W). Some cards are using two 8-pin connectors, but this has not been standardized yet, therefore such cards must not carry the official PCI-Express logo. This configuration would allow 375 W total (1×75 W + 2×150 W) and will likely be standardized by PCI-SIG with the PCI-Express 4.0 standard. The 8-pin PCI-Express connector could be mistaken with the EPS12V connector, which is mainly used for powering SMP and multi-core systems.
Pci-exp 16x 2.0
The power spec has also been increased. A new version of the power supply connector that is used for graphics cards that need more power than the slot can deliver (sometimes called a PEG connector, for PCI-Express Graphics) has been introduced, changing from 6 pins to 8. A single x16 card may now draw up to 300 W of power (
75 W from the slot itself, 150 W from an 8-pin PEG connector, 75 W from a second PEG connector), up from 225 W (
75 W from the slot, 75 W each from 2 6-pin PEG connectors) or originally 150 W (
75 W from the slot, 75 W from a 6-pin PEG connector).
