The MSI MEG Ai1300P PCIE5 1300W PSU Review: The ATX 3.0 Era Has Begun

In light of the new ATX 3.0 standard, we took a shot at adding power excursion compliance testing into our articles. Given that this is the big addition to the ATX 3.0 specification– and indeed its very reason for being – it’s where we would like to see if PSUs are truly living up to the very high standards set by the new specification.

Unfortunately, the testing requirements of the new standard have proven too high for our equipment – and that of the majority of small laboratories – to meet. The power excursion specifications suggest electrical current-to-time figures that are extremely short. For example, taking the MEG Ai1300P of this review into consideration, for the single case of the 200% power excursion testing, we would need to test that it can handle 2600 Watts for 0.1 ms. Assuming a starting load of about 800 Watts and 65 A on the 12 V rail, the 12 V load would have to get up to 215 A and back down to 65 A within 0.1 ms. Furthermore, according to Intel’s testing guide, this would have to continue for at least a minute, which means at least five hundred cycles in this scenario.

In an ideal world, we would just enter the current and time figures into the software and our electronic loads would run the test, instantly getting the load up to 215 A for 0.1 ms and then immediately back down to 65 A for 1.9 ms, according to the guide’s requirements.

In the real world, however, there is no such thing as “instantly”. Electronic loads, like any other device that is bound by the laws of physics, require time to react. The speed at which an electronic load can increase its amperage is called Ramp (or Slew) Rate and our larger loads have an ideal Slew Rate of 0.5 A/μS. Assuming that they operate linearly and exactly as specified, which no electronic load does for a variety of reasons, our two primary electronic loads in parallel would require at least 0.15 ms (150 μS) just to get the load up at 215 A. They would also require time, albeit less than half of it, to get the load back down to 65 A. When the test dictates a test time of 0.1 ms and the testing equipment requires at least twice that much time just to react, it goes without saying that testing results are highly unreliable.

Nevertheless, we took a shot at testing the power excursion capabilities of the MSI MEG Ai1300P PCIE and of the few ATX 3.0 compliant units that we currently have available. We took two approaches: one by assuming that our electronic loads are “ideal” and programmed the exact duty cycle figures that Intel dictates in their guide, and one by trying to take into account the real slew rate times of our loads and calculate the RMS equivalent duty cycle.

Both of our approaches ultimately failed, as all of the PSUs we currently have available would shut down at most tests above 120% power excursion – therefore we need not worry about our loads being insufficient to test the MEG Ai1300P at 200% excursion (we are also currently limited to 2400 Watts on the 12V line). Theoretically, testing with the RMS-equivalent duty cycle times should work and the PSUs should not be shutting down, yet we cannot claim that the units are not technically capable of meeting their specifications when our equipment is not meant to be running such tests.

Intel requires the PSUs to have a slew rate of at least 5 A/μS, so an electronic load must be at least as fast as that figure to be able to perform ATX 3.0 compliance testing. From a professional’s point of view, proper testing would require the testing equipment to be at least 30% faster than the absolute minimum required. This requires a highly advanced (and expensive) electronic load with multiple modules, like the Chroma Mainframe and High-Speed modules Intel themselves is using, which has a total slew rate of 8 A/μS and it would need only 0.02 ms to get the load from 65 A all the way up to 215 A – and that still is 20% of the test’s required 0.1 ms time in our example, a figure that many experts would find far too great for precise measurements.

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

The efficiency of the MSI MEG Ai1300P does meet the 80Plus Platinum certification requirements when it is powered from an 115 VAC source. However, when the main’s voltage is 230 VAC, the efficiency is raised by an average of 1%, which is not enough to meet the 80Plus Platinum requirements for that input voltage. The average nominal load efficiency (20% to 100% of the unit’s capacity) is 92.1% with the unit powered from a 230 VAC source, and drops down to 91.3% if the unit is powered by a 115 VAC source. It is also interesting to note that its efficiency under very low loads is quite high, at above 83% for a 5% load.

The fan of the MSI MEG Ai1300P PCIE5 is thermally controlled by default, with the unit keeping it disabled until the load was over 430-440 Watts. Regardless, the internal temperature of the PSU is quite low considering the massive power output. Once the fan does start, it is very quiet at first but then speeds up very quickly as the load increases, making the Ai1300P clearly audible when the load is greater than 800 Watts.

The resistance of the MSI MEG Ai1300P PCIE5 unit to adverse ambient conditions is astonishing, with the unit hardly affected at all while operating inside our hotbox. There is a practically negligible efficiency degradation of 0.2-0.3% depending on the load, a figure four to six times lower than other similar designs. There is very little additional degradation under heavy loads, suggesting that the components of the MSI MEG Ai1300P PCIE5 are not thermally stressed at all.

Despite the exceptional resilience of the PSU against high ambient temperatures and its 80Plus Platinum efficiency levels, the losses of a unit this powerful sum up to over 100 Watts under high loads. These losses do increase the internal temperature of the PSU significantly but the cooling system of the MSI MEG Ai1300P PCIE5 proves to be more than adequate, as the temperature of the critical components does not get anywhere near critical levels during our testing. As a matter of fact, the MSI MEG Ai1300P PCIE5 delivers lower temperature figures than many units with significantly larger bodies and fans do.

The sizable heatsinks of the MSI MEG Ai1300P PCIE5 seem to be collaborating excellently with the 120 mm PowerLogic fan at keeping the temperature of the critical parts low. With the PSU inside our hotbox, the fan started quicker and sped up even faster, reaching its maximum speed while the PSU was at just 70% load. Regardless, the internal temperatures of the unit kept rising almost linearly and were kept within safe levels.

As part of our testing, we also check output parameters are within specifications, as well as voltage ripple and line noise.

The electrical performance of the MSI MEG Ai1300P PCIE5 1300W PSU is very good overall. Our instruments recorded a maximum ripple of 32 mV on the 12V line with a recommended design limit of 120 mV, an excellent figure for a PSU with that kind of power output. The filtering of the minor voltage lines is even better, with a maximum of 12 mV and 14 mV on the 3.3V and 5V lines respectively. Voltage regulation on the minor lines is very tight, with both lines staying within 0.8% across the load range. Strangely, especially for the CWT platform, the voltage regulation of the 12V line is much looser, at nearly 2%. This still is a very good figure but uncharacteristic of the particular OEM or class of this PSU.

As part of our standard testing, we test the primary protections of all PSUs we review (Over Current, Over Voltage, Over Power, and Short Circuit). The MSI MEG Ai1300P PCIE5 successfully passed all of the tests, generally reacting timely when needed and shutting down to protect itself and the components it is powering. The OCP protection is a little slow but does kick in when necessary – probably a side effect of the high power excursion figures dictated by the ATX 3.0 standard.

Testing the 12VHPWR Cable: 600+ Watts Sustained

Finally, at this point we should also address a topic that concerns many users who are in the market for a card requiring a 12VHPWR connector. There have been multiple publications and reports of such connectors melting and even causing serious damage to the cards. Many of these reports are definitely true and the culprit would seem to be a very poorly designed PCIe 8-pin to 12VHPWR adapter that is supplied with some of the graphics cards. These adapters are based on a greatly overloaded busbar design and makes use of even fewer power wires. However, because of those reports and a hoard of false information posted all around the place, many users began to fear that all 12VHPWR connectors are incapable of actually powering 600 Watt graphics cards.

In order to shed some light on these claims – and also because some PSU manufacturers are making wild amperage claims – we decided to thoroughly test the native 12VHPWR cable that came with the MSI MEG Ai1300P PCIE5.

We should begin by mentioning that yes, the new connector is very tightly rated, unlike its predecessors. Nevertheless, the 9.3 A per pin rating it has means that the connector should be able to handle that much current without any damage (6 × 9.3 A = 55.8 A or about 670 Watts). We could not run the MEG Ai1300P PCIE5 at exactly that figure for prolonged periods of time because the OPP/OCP protections would kick in and shut down the PSU, yet we did manage to get it running for 30 minutes with a current of 51 A (8.5 A per pin, 612 Watts).

Under these conditions, the connector reached a maximum temperature of 61 °C. With another product, where the OCP protection was a little slack, we managed to keep it running with a current of 8.8 A per pin and managed to reach a temperature of 68 °C. Even though these figures are borderline safe for PVC insulation (70 °C surface or 90 °C conductor temperature maximum), they are ultimately safe and within the allowances of the specification.

What we tested is also an extremely unlikely scenario for the moment, as no graphics card can currently be drawing 600 Watts constantly – it would itself melt. Even by taking the massive 3× power excursions into account, the average power draw of any card over practical lengths of time is significantly lower than 600 Watts – therefore, the cable should never reach temperatures that may become a concern.

Therefore, we believe it’s reasonable to say that any properly made 12VHPWR cable, with twelve power wires at least as thick as the design standard dictates, should be perfectly safe to use.

The MEG Ai1300P PCIE5 marks a lot of milestones for MSI – it is their first ATX 3.0 compliant unit, the world’s first ATX 3.0 compliant unit, and currently their flagship PSU product. Needless to say, the MEG Ai1300P has to meet very high expectations, both by the users and by MSI themselves.

MSI placed a lot of effort into the uniqueness of the MEG Ai1300P in terms of appearance. The company went with a fully customized chassis and metallic side decorations, using contrasting body colors but not fancy lighting, for a seamless and elegant look. From a practical point of view, the chassis of the massively powerful unit is just 160 mm long, making it compatible with any ATX-compliant case. The odd point here is the two cables which are fully sleeved instead of having individually sleeved wires like the rest of them.

In terms of electrical performance, the MSI MEG Ai1300P PCIE5 does deliver. Keeping its massive power output in mind, the MEG Ai1300P manages outstanding power quality, with excellent voltage regulation and remarkable filtering. MSI’s engineers did not neglect the minor voltage lines either, which often are not as well filtered as the main 12V line. The efficiency of the MEG Ai1300P barely meets the 80Plus Platinum certification standards but it is extremely stable and practically unaffected by high ambient temperatures. It also is very efficient at very low loads, which is important for a unit with a very high-power output.

The use of a 140 mm fan was not possible due to the small chassis, forcing MSI’s engineers to resort to a 120 mm fan. Although the quality of the fan is exceptional, its smaller size of it inevitably means that it needs to spin faster in order to create the required airflow. This does not necessarily mean that all 135/140 mm fans would be quieter but most quality products would generate at least a little less noise for the same amount of airflow. Ultimately, the fan of the MEG Ai1300P does a great job at keeping the internal temperatures of the PSU very low but it does get noisy when the load and/or the ambient temperature are very high.

To summarize, the MSI MEG Ai1300P PCIE5 is a powerful PSU, very well made and with very good overall performance. Currently, its primary selling point is the ATX 3.0 compliance and the new 12VHPWR/PCIe 5.0 connector, which is in our opinion a necessity for anyone who is going to purchase a graphics card that uses it. While many older PSUs can handle the power requirements of such a card, there are frequent issues with the 12VHPWR adapters and it is counterintuitive to risk damage to a $1000+ card for the price of a great PSU.

When it can be found in stock, the MEG Ai1300P currently retails for $360, which is quite high for a PC PSU, yet not unreasonably high considering the current state of the market and the features it offers. Builders who do not currently intend to use an NVIDIA RTX 4000 series card card but also frequently upgrade should also consider the MEG Ai1300P, as it should last them for many years and endless system changes/upgrades without having to swap a PSU again.