Radeon HD 5770: PCB Design and Cooling System

The Radeon HD 5770 is very much alike to its elder brother. It has a square black casing with red strip but the card is substantially shorter at 20.5 centimeters against the Radeon HD 5870’s 27 centimeters. Owners of small system cases should appreciate this compactness.

The reverse side of the card looks more exciting than that of the Radeon HD 5870 as it caries half the memory chips and the controllers of the GPU and memory voltage regulators. The cooling system can be easily dismantled by unfastening four screws on the X-shaped back-plate. The other screws fasten the heatsink of the memory chips on the face side of the PCB. The face side looks like this:

Being compact, the PCB is populated heavily. There is little free room left. The power circuit follows a 3+3 design with 3 power phases in both the GPU and memory voltage regulators. One of the memory power phases is located near the CrossFire connectors. Looks redundant for a Juniper-based solution, but there is nothing bad in having more stable power.

The GPU voltage regulator seems to be managed by an L6788A controller from STMicroelectronics. A pair of uP7701 seem responsible for power supply of memory chips.

The card has one 6-pin PCIe 1.0 connector for additional power. This should be quite enough for an RV830 even at extremely high frequencies.

The Radeon HD 5770 is equipped with GDDR5 memory in 1Gb, 1.5V chips from Hynix (H5GQ1H24AFR-T2C). The T2C suffix denotes a rated frequency of 1250 (5000) MHz. The card’s actual memory frequency is lower at 1200 (4800) MHz. The RV830 has a 128-bit memory bus, so its peak memory bandwidth is 76.8GBps which is much lower than the Radeon HD 4890’s memory bandwidth of 124.8GBps. Theoretically, this may prove to be a bottleneck when running resource-consuming games at high resolutions with full-screen antialiasing.

The die of the RV830 Juniper has a rectangular shape. The marking is still unclear for the uninitiated except for the manufacture date. This sample is dated the 34th week of 2009, i.e. the end of August. The die lacks a protective frame.

As we’ve already said, the Juniper is similar to the RV770/790 in its specs. It too has 800 ALUs grouped into 160 universal shader processors. It also has 40 texture processors and 16 RBEs. The core frequency of the Radeon HD 5770 is 850MHz.

Like its elder brother, the Radeon HD 5770 supports up to three monitors simultaneously, offering two DVI-I ports, one HDMI connector and one DisplayPort. Of course, it also supports CrossFireX configurations and has two appropriate onboard headers.

The cooling system of the Radeon HD 5770 is a smaller copy of the Radeon HD 5870’s cooler. It consists of a copper base, connected with a heat pipe to an aluminum heatsink, and a casing with blower.

You can see the trace of traditional dark-gray thermal grease on the cooler’s base. A sealed end of the heat pipe can be seen in the bottom right. Below you can see the grooves for the air to go sideways from the mounting plate. The photo shows the model of the blower. It is a well-known Delta BFB1012 that is used in many products from ATI an Nvidia.

The heatsink is rather small and the flat heat pipe serves to distribute the heat uniformly in the base rather than to carry it on to the farthest edge of the heatsink.

The memory chips on the face side of the PCB are cooled with a metallic plate with low ribbing that has elastic thermal pads. Something like that was used in the cooling system of the Radeon HD 4770. As we’ve said already, the GDDR5 chips on the reverse side of the PCB are not cooled at all. This cooler doesn’t look like a record-breaking solution, but should cope with cooling a Radeon HD 5770 considering the latter’s low power consumption.