Almost all RTX 4090 cards have an increased maximum TGP, which is “Total Graphics Power”, for overclocking. There are models with TGPs as low as 500W (ZOTAC); however, most GPUs go much higher. There are models with a maximum power of 600W such as NVIDIA Founders Edition, ASUS ROG Strix or Gigabyte Gaming. But until Neptune’s announcement, none of the cards had been higher before.
From the Colorful iGame line, the iGame Neptune is a liquid-cooled RTX 4090. Although it shares a PCB with the iGame Vulcan series, the clock speed is slightly higher (2640MHz vs 2625MHz). The maximum TGP of 630W is also greater (80W higher than Vulcan).
This TGP is the highest TGP currently supported by an RTX 4090 GPU. That’s why Colorful recommends using a 1000W power source.
Custom RTX 4090s would at some point exceed the 600W TGP limit, but such settings were to be expected from enthusiast OC cards like the upcoming Galax HOF.
The Neptune has been sent for reviews; however, it seems that few have been published yet. The Expreview team has published a review and they have validated that the device comes with a standard TGP of 550W and a maximum of 630W. Performance was not affected by unlocking an extra 80W of power because the 100W higher standard TGP was already so high. In 3DMark Time Spy Extreme, the card’s performance gain was only 0.7%.
In addition, despite the card’s default TGP of 550 W, the maximum value measured with the NVIDIA PCAT power monitoring program was only 470 W. A complex water cooling system also contributed to the unusually high power consumption of 47 W idle.
For graphics cards with non-standard 450W+ TGP, enthusiasts should pay special attention to the 12VHPWR connection. A review by TechPowerUP found no difference between the 450W and 600W versions of this connection when used with 450W RTX 4090 GPUs. A 600W cable is highly recommended for any card that exceeds standard TGP, especially manual and factory overclocked GPUs.
In addition, the 600W requirement can be met by connecting four 8-pin power cables to 12VHPWR converters. When only three 8-pin cables are used, this NVIDIA smart adapter reverts to the 450W standard. Igor’sLAB has discussed this extensively. It is important to remember this when selecting a card, such as the iGame Neptune.