|Gigabyte GeForce GTX 480 SOC GV-N480SO-15I|
|Reviews - Featured Reviews: Video Cards|
|Written by Bruce Normann|
|Wednesday, 22 December 2010|
Page 2 of 21
Closer Look: Gigabyte GTX 480 SOC
The Gigabyte GV-N480SO-15I GeForce GTX 480 Super Over Clock video card couldn't be further from the reference card. The first thing you notice when you pick up this video card is that it doesn't seem as densely constructed as some other cards in this price and performance range that have a single radial blower. The Windforce 3X cooling assembly doesn't look or feel like a brute force approach to GPU cooling. Sure, the heatsink/fin assembly, and the heatpipes and the three fans add some weight, but it's modest. This is the turbocharged flat-six approach to performance, not the Detroit Iron way. Later, we'll see that it doesn't sound like brute force either, which is a very good thing.
The fan shroud is a very open design; there is very little chance that a major portion of the airflow is being directed to the rear outlet. After the air passes through the fin assembly, it hits the components mounted on the face of the card, at least on the two ends. The center section is taken up by a fairly large combination of copper vapor chamber, aluminum mounting plate, and heat pipes. The three fans are angled in different directions, and the fin assemblies under each fan are independent units, that are laid out 90 degrees apart. All three fans are identical three-wire types with a tachometer output, and have an indicated maximum operating speed of 4075 RPM.
With high-end video cards, the cooling system is an integral part of the performance envelope for the product. Make it run cooler, and you can make it run faster, has always been the byword for achieving gaming-class GPU performance. The Gigabyte GTX 480 SOC has a very complex and sophisticated design for its cooling device, combining a vapor chamber and three 6mm diameter heatpipes. At first glance, it looks like four heatpipes exit from the central area, but one of them does a U-turn in there, so the total count is only three. None of the heatpipes passes directly over the center of the GPU die, and instead rely on the copper vapor chamber to transfer the heat over to the pipes. Once they exit, the pipes spread to the outer reaches of the aluminum fin assembly, two to the right and two to the left.
The layout of the various elements of the cooler design is a little easier to see in this straightforward view from the GPU's perspective once the cooler is removed. In addition to the contact patch for the GPU, the main mounting plate has multiple locations for thermal interfaces with the DRAM chips, which are easy to spot by the light blue foam tape. There was good, even compression on the soft thermal tape used to equalize the surface heights of the various devices, but a couple of the GDDR5 memory chips seem to have been left out in the cold. The driver transistors for the VRM Output section are clamped under a thin heatsink on the top side of the board, while the high-side and low-side outputs are mounted on the back side and are left to their own devices as far as cooling goes.
The copper mounting plate of this cooler is actually a vapor chamber instead of a solid block of metal. Rather than acting like a true heat-sink, where short heat pulses are absorbed quickly into a large thermal mass, this design relies on the high thermal conductivity of the vapor chamber to transfer heat quickly to the heat pipes, and then over to the aluminum fins where it gets transferred to the passing air. The fact that the heat pipes are nowhere near the center of the GPU package tells you that this is a completely different type of design than we're used to seeing.
The power for the Gigabyte GTX 480 SOC enters into one 6-pin and one 8-pin PCI Express connector at the far end of the board. There are several chokes and capacitors right at the input to do the bulk filtering of DC power coming in. This is the first chance the board has to knock down any nasties coming in from the power supply. Noise, voltage spikes, dropouts, and other transients should all be stopped right here. On the bottom corner of the board is the BIOS select button, which switches between the two independent BIOS chips installed on the card: the SOC (Super Overclock Series) Default BIOS and LN2 BIOS. The LN2 BIOS prevents the Cold Bug phenomenon that causes the GPU to freeze up at extremely low temperatures.
The layout on the front and back of the printed circuit board is very typical for a high-enc video card. The large number of power supply components mounted on the back side is a matter of necessity, both from a space standpoint and for thermal reasons. The lack of any heatsinks on the 24 primary power MOSFETs in the VRM section is a question mark, but the fact that there are so many of them, means there is more surface area to dissipate heat.
This non-reference card from Gigabyte is simpler in some ways than the basic NVIDIA design; maybe more straight forward is a better description. I doubt that it is as cheap to produce as the original GTX480, with all the enhancements to the power supply, and the trick cooling section. Every added dollar that went into the redesign went towards making the card faster and more conducive to further overclocking by the customer. It's hard for me to argue with that approach; it's the one I'd be most inclined to take, given a choice.
In the next section, let's take a more detailed look at some of the new components on this decidedly non-reference board. I did a full tear-down, so we could see everything there is to see...