AMD Radeon HD 7770 and 7750 Specifications and Review

AMD Radeon HD 7770 GHz Edition

The Radeon HD 7770’s 1 GHz Cape Verde GPU employs all 640 available shaders, theoretically yielding 1.28 TFLOPS of compute performance. Since each Compute Unit includes four texture units, 7770 also sports 40 texture units. An unmolested back-end turns up four ROP partitions and a 128-bit memory bus populated by 1 GB of GDDR5 memory at 1125 MHz. Measuring 8.5” long, this dual-slot card’s dimensions are almost identical to the Radeon HD 5770.
Whereas that older Juniper-based board uses a centrifugal fan to exhaust heat, the 7770 employs an axial fan mounted on an aluminum extruded heat sink. We’re normally not advocates of designs that recirculate hot air. However, an 80 W typical board power rating is conservative enough that other subsystems in a closed chassis shouldn’t be affected.

AMD Radeon HD 7770

That 80 W rating exceeds the PCI Express bus’ 75 W limit, so the Radeon HD 7770 does require one six-pin auxiliary power connector. Even still, the 5770 was rated at 108 W—almost 30 W higher. Even more impressive, AMD’s Radeon HD 7770 benefits from the company’s suite of ZeroCore technologies, which purportedly take power use under 3 W during long idle periods.
Compared to the 7750, the 7770 has 25% more CUs and a 25% core clock advantage, giving it a massive 56% shader and texture performance advantage over the 7750. With the 5700 series this gap was only 35%, and most of that was a result of core clock differences. The fact that the memory bandwidth is the same between the 7770 and 7750 equalizes things somewhat, but it’s still a huge difference for two cards that are in the same family.

AMD Radeon HD 7750

This brings us back to where we started: how AMD is covering the entire $109+ market with only 3 GPUs. Between the massive performance gap between the 7700 series cards and the fact that the 7750 is a sub-75W part, it becomes increasingly obvious that the 7700 series is the de-facto replacement for both the 6600 series and the 5700 series.
The 7750 will fill the 6670’s old role as AMD’s top sub-75W card, but as we’ll see its performance means it won’t be a complete replacement for the 5700 series. Instead the role of replacing the 5700 series falls to the much more powerful 7770.

AMD Radeon HD 7750

 The 7750 will be up against AMD’s 5770/6770 and the absolute cheapest of NVIDIA’s GTX 550 Ti cards. Meanwhile the 7770 will be competing with AMD’s 6850 and 6870, along with NVIDIA’s GTX 460 and their cheapest GTX 560s. 

SPECIFICATIONS and COMPARISON

	AMD Radeon HD 7770 GHz Edition	AMD Radeon HD 7750	AMD Radeon HD 6850	AMD Radeon 5770	AMD Radeon HD 5750
Stream Processors	640	512	960	800	720
Texture Units	40	32	48	40	36
ROPs	16	16	32	16	16
Core Clock	1000MHz	800MHz	850MHz	850MHz	700MHz
Memory Clock	4.5GHz GDDR5	4.5GHz GDDR5	4.8GHz GDDR5	4.8GHz GDDR5	4.6GHz GDDR5
Memory Bus Width	128-bit	128-bit	256-bit	128-bit	128-bit
Frame Buffer	1GB	1GB	1GB	1GB	2GB
FP64	1/16	1/16	N/A	N/A	N/A
Transistor Count	1.5B	1.5B	2.15B	1.04B	1.04B
PowerTune Limit	100W	75W	N/A	N/A	N/A
Manufacturing Process	TSMC 28nm	TSMC 28nm	TSMC 40nm	TSMC 40nm	TSMC 40nm
Architecture	GCN	GCN	VLIW5	VLIW5	VLIW5
Price Point	$159	$109	~$149	~$99	~$89