PCB Design and Functionality
EVGA GeForce GTX 285 FTW and Zotac GeForce GTX 285 AMP!
Since both these graphics cards use reference PCB design and a cooling solution developed by Nvidia, we won’t go too much into details about them now, because we have already discussed the reference layout in our GeForce GTX 285 review before. In fact, the only distinguishing feature of these two solutions is the brand name logo sticker on the cooler casing. Zotac’s sticker bears a fire-spouting dragon, while EVGA’s sticker depicts a barrel of some sci-fi weapon:
The PCB of both cards is 27cm long, which makes them unfit some certain system cases with shorter base and specific HDD chassis design. However, those who will be building a gaming SLI platform will definitely make sure that their case is big enough for a system like that.
Unlike GeForce GTX 280, all GeForce GTX 285 memory chips are located on the front of the PCB. As a result, the PCB layout as well as the cooler is made way simpler.
The voltage regulator circuitry includes a six-phase regulator for the GPU managed by Intersil ISL6327 controller and a two-phase regulator for the video memory managed by an unknown chip of microscopic size. On EVGA GeForce GTX 285 FTW this chip is marked as BR=AL U07, and on Zotac GeForce GTX 285 AMP! - as BR=AG E1V.
Although both solutions have increased GPU and memory frequencies and one of the spots on the PCB is designed for 8-pin PCIe 2.0 connector with up to 150W load capacity, the cards are equipped with a pair of regular 6-pin PCIe 1.0 connectors designed for 75W load. Since G200b has lower power consumption than G200, it should be more than enough, although we know that during overclocking these connectors may be receiving up to 70W of power, which is rather close to their maximum capacity. A small two-pin connector should be used for S/PDIF to HDMI translation to the sound card. As we have already mentioned, there is a special cable for that bundled with both cards. This solution is not as convenient as the one from ATI that integrated a sound core with HDMI support into their graphics processors. However, there is nothing you could actually do about it: Nvidia solutions do not know yet how to work with sound streams on their own.
Both graphics cards have 16 512Mbit GDDR3 memory chips onboard (16Mx32) that form a 1024MB bank with 512-bit access. According to Nvidia’s official specifications the reference memory frequency for GeForce GTX 285 is 1242 (2484) MHz. However, the video memory on Zotac and EVGA solutions we are discussing today has been pre-overclocked by the manufacturers:
EVGA GeForce GTX 285 FTW
Zotac GeForce GTX 285 AMP!
As you can see, EVGA GeForce GTX 285 FTW was overclocked somewhat more aggressively – to 1323 (2646) MHz, while Zotac GeForce GTX 285 AMP! was overclocked to 1296 (2592) MHz. As a result, the peak memory subsystem bandwidth is a little higher: 169.3GB/s vs. 165.9GB/s respectively. The difference in percents is only 2%, so you will barely notice it in real gaming conditions.
The GPUs have also been overclocked. The official default frequencies for the main and shader GeForce GTX 285 core domains are 648 and 1476MHz respectively. However, EVGA GeForce GTX 285 FTW core works at 702/1584MHz and Zotac GeForce GTX 285 AMP! Core – at 702/1512MHz. So, EVGA graphics card has an advantage in shader processors speed. It is interesting that EVGA GeForce GTX 285 SSC we have tested before worked at the same GPU and memory frequencies, but the official company web-site has no mention of this product anymore. The only pre-overclocked GeForce GTX 285 models listed there are GeForce GTX 285 FTW and GeForce GTX 285 Superclocked. Looks like EVGA GeForce GTX 285 SSC may have got a new suffix in the model name. As for Zotac GeForce GTX 285 AMP!, it is, on the contrary, not a flagship solution in the product lineup – there is Zotac GeForce GTX 285 Infinity above it overclocked to 722/1548 MHz. However, it needs to be included into the existing liquid-cooling contour, so we can’t call it a fully independent solution.
Since both graphics cards are an exact copy of Nvidia’s reference design, they have all standard connectors, including a pair of dual-channel DVI-I ports, seven-pin mini-DIN for the analogue video out and two MIO interface connectors providing the cards with Triple-SLI support. There is a plastic light pipe on the card’s mounting bracket next to the mini-DIN connector. It comes from the green and red LEDs indicating normal functioning (green) or reporting any existing power supply issues (red).
As we have already said, GeForce GTX 285 has a simpler cooler than GeForce GTX 280. The new cooler has a smaller heatsink and extremely simple cooling system for the voltage regulator components: they are simply cooler by the fan blowing air through the slits in the heatsink base.
The heat from the memory chips moves through fibrous pads soaked in white thermal paste. The base of the heatsink on top of the GPU itself is covered with a layer of thick dark-gray thermal interface.
We can’t say that the GeForce GTX 285 reference cooler is simple in design. However, it is very thoroughly made and boasts good cooling efficiency with pretty comfortable though not record-breaking acoustics.
The users will be more than pleased with it for the most part and will not need to search for alternatives of any kind. Only those who need a completely silent solution or extreme overclocking enthusiasts in hunt for a new 3DMark world record may want to replace the default cooler with a liquid- or even cryogen-system.