Corsair AX1500i Power Supply Review
Corsair's flagship power supply unit (PSU) offering, the AX1500i, is the best PSU money can buy today, according to many experts in the field. The AX1500i stands out not only because of its extremely high performance but also its rich features and digital platform. Currently, the AXi series is Corsair's top PSU line, consisting of four digitally controlled units with capacities ranging from 760W to 1500W. The introduction of this line was made with the AX1200i model, which easily conquered the top place in its category; afterward, Corsair released the two lower-capacity AXi models. In 2014, Corsair took a huge step forward with the introduction of the AX1500i, which features significant improvements compared to the other AXi PSUs. The AX1500i is the only PSU in this line that meets the 80 Plus Titanium efficiency requirements, which is a massive accomplishment, considering the huge capacity of the unit.
So far, we have seen several digital PSUs from various manufacturers, including CWT, Enermax and Etasis. However, none of them offers a fully digital power supply, meaning that, in most cases, only a few circuits are digitally controlled and analog controllers are used for the rest. For most manufacturers, the main reason for not going fully digital is related to increased production costs. But for digital circuits, you also need an experienced engineering team to leave analog designs behind. Currently, the AX1500i and the AX1200i units feature an almost fully digital platform, as all rails except for the 5VSB rail — along with the APFC converter, the primary side and the protections of the PSU — are controlled by processors, not by analog controllers. If the 5VSB circuit featured digital control as well, then the platform could be considered a purely digital platform. In terms of optimal performance, the 5VSB rail isn't important enough to justify the increased costs of a digital circuit.
In addition to offering Titanium efficiency, the AX1500i PSU is Haswell-ready and can deliver its full power continuously at up to 50 degrees Celsius (122 degrees Fahrenheit). Strangely enough, in the protection features section, we don't see overpower protection (OPP) listed. However, we think it is present, because once we tried to overload the PSU with more than 1550W, it shut down after a while. Two major features of the AX1500i are the fully modular cabling design, which is essential in a PSU with so many cables and connectors, and the fluid dynamic bearing (FDB) fan, which is most helpful for increasing the PSU's reliability and longevity. The operation of the FDB fan is supported by a semipassive mode that can be disabled through the provided software.
The AX1500i has large dimensions and weight, which is normal, since it is a real powerhouse. However, we have recently seen some PSUs in this category with significantly smaller dimensions (e.g., the SilverStone ST1500-GS), but we should note that none of them comes close to the performance levels that the AX1500i achieves. The warranty period for the AX1500i is very long — seven years — showing Corsair's confidence in its platform. While the price is quite high, given the technology that this platform features, we believe it is justified.
|Total Max. Power (W)||1500|
The +12V rail can deliver the unit's full power alone, and this means a huge max current output that reaches 125 A. The minor rails are very strong as well, with 180 W max combined power. The 5VSB rail has enough power at 3.5 A, although, in a mega-PSU like this, we would like to see at least 4 A on this rail.
Cables And Connectors
|Description||Cable Count||Connector Count (Total)|
|ATX connector 20+4 pin (710mm)||1||1|
|4+4 pin EPS12V (800mm)||1||1|
|4+4 pin EPS12V (650mm)||1||1|
|6+2 pin PCIe (700mm+150mm)||2||4|
|6+2 pin PCIe (800mm)||2||2|
|6+2 pin PCIe (650mm)||4||4|
|4 pin Molex (450mm+100mm+100mm+100mm)||3||12|
|FDD adapter (+100mm)||2||2|
|PMBUS cable (+800mm)||1||1|
|USB Mini to Motherboard Header cable (+800mm)||1||1|
The AX1500i comes with a multitude of cables, including 10 PCIe connectors, 20 SATA connectors and 12 peripheral connectors. Essentially, you will be able to power everything with this unit. In fact, we don't remember any other PSU having this many SATA connectors, so if you want to build a file server, this looks like the ideal PSU to power it. As you can see from the last two rows of the table above, Corsair also provides the suitable cables that will allow you to connect this unit either to a Corsair Link Commander or directly to a USB header on your system's mainboard.
Overall, cable length is satisfactory, but we would have liked the four-pin Molex connectors to be farther apart, since usually, the components that are fed by these connectors are not close to one another. Finally, the 24-pin ATX connector and all EPS and PCIe connectors use 16-AWG wires for lower voltage drops at high loads, whereas the rest of the gauges are 18 AWG.
Through the Corsair Link application, you can enable overcurrent protection (OCP) for each of the 10 eight-pin sockets onto which the PCIe and EPS cables are attached. This means that power distribution is optimal, and you also can set a custom OCP level, with the maximum being 40 A for each of the virtual rails.