Radeon 4770 specs

Product positioning

The Radeon 4770 is in a bit of a strange position. Based on its branding, you’d assume that it’s inferior to ATI’s Radeon 4830 GPU, but actually in benchmarks it’s faster. When we asked ATI if this meant the end of the 4830 though, they said they’d continue to produce it for interested board partners, apparently the 4830 is selling extremely well in Europe and Asia, so some partners may not retire it just yet. According to ATI’s official press presentation though, the 4830 is no longer depicted, with the 4770 occupying the $99 sweet spot (keep in mind this is $99 after a $10 mail-in rebate), the Radeon 4850 512MB priced just above it at $139, 4850 1GB at $159, and the Radeon 4870 512MB and 1GB carrying MSRPs of $169 and $199 respectively.

So how does the Radeon 4770 manage to deliver such impressive performance for its price tag? The key lies in its clock speeds and ATI’s use of high-speed GDDR5 memory. Take a look at the GPU’s specs:

Radeon 4700/4800 Series Comparison
	Radeon 4770	Radeon 4830	Radeon 4850	Radeon 4870
Manufacturing Process	40-nm	55-nm	55-nm	55-nm
# of Transistors	826M	956M	956M	956M
Core Clock Speed	750MHz	575MHz	625MHz	750MHz
# of Stream Processors	640	640	800	800
Compute Performance	960 GFLOPS	740 GFLOPs	1.0 TFLOPs	1.2 TFLOPs
Texture Units	32	32	40	40
Texture Fillrate	24 GTexels/sec	18.4 GTexels/sec	25 GTexels/sec	30 GTexels/sec
ROPs	16	12	16	16
Pixel Fillrate	12 GPixels/sec	9.2 GPixels/sec	10 GPixels/sec	12 GPixels/sec
Memory Type	GDDR5	GDDR3	GDDR3	GDDR5
Memory Clock Interface	128-bit	256-bit	256-bit	256-bit
Memory Clock Speed	800MHz (3.2GHz effective)	900MHz (1.8GHz effective)	1000MHz (2.0GHz effective)	800MHz (3.2GHz effective)
Memory Bandwidth	51.2GB/sec	57.6GB/sec	64GB/sec	115GB/sec
Memory Size	512MB	512MB	512MB/1GB	512MB/1GB
Max Board Power	80W	110W	110W	160W
Power Connector	1x6-pin	1x6-pin	1x6-pin	2x6-pin

New cooling

With its 40-nm manufacturing process, you’d naturally expect the Radeon 4770 to utilize a single-slot cooler. After all, the 4830 and 4850 got by just fine with their single-slot cooling. So why does the 4770 reference design ship with a dual-slot heatsink/fan unit? The answer certainly is due in part to the GPU’s 750MHz core clock frequency, that’s the same speed as the Radeon 4870. ATI also heard the criticism from end users regarding the 4850’s stock cooling, so they decided to address this issue for the 4770. In our testing the Radeon 4770 idled at around 54 degrees Celsius – the same speed as our 4830 reference board – but the key difference is load temps. Whereas the 4830 hit 80 degrees in our testing under load, the 4770 maxed out at 71 degrees.

That’s still a few degrees higher than we’d like to see ideally, but it’s a world of difference in cooling. While we could literally burn our fingers on our 4830 and 4850 reference boards if we weren’t careful removing them from the testbeds after extended testing sessions, the 4770 was merely warm to the touch. The card’s cooling operates very quietly as well (under 40 dB), leaving room for enthusiasts to crank up the RPMs if they wish to get load temps under the 70 degree range and still have a quiet-running graphics card.

The cooler design itself is similar in shape to ATI’s cooler previously used on the 3870, however the 4770’s cooling unit is more powerful. ATI adds two copper heatpipes to the list of ingredients, while a dual-slot aluminum heatsink is responsible for drawing heat off the heatpipes. Finally, a blower-style fan exhausts hot air from the GPU outside your case. ATI even adds aluminum heatsinks for cooling the board’s GDDR5 memory modules while an aluminum plate helps draw heat off the PCB itself.

Despite its 40-nm interface, the Radeon 4770 does require a six-pin PCIe power connector. According to ATI the board draws up to 80W of juice, which is just 5W more than the PCIe interface itself can supply to the card.


But the reference board ATI sent over isn’t the only 4770 we have on-hand. ASUS also managed to overnight one of their EAH4770 boards to us just in time for a photo shoot (the card is clocked at the stock 4770 clocks, so performance is similar to our ATI reference board).

As you can see, the ASUS EAH4770 sports a dual-slot cooler that’s entirely different than the board ATI sent over. At first we thought it was a custom design, but a quick check of 4770 listings on Newegg reveals that other board partners are using the same cooling design. We’ll have to check with ATI to see what’s going on with 4770 cooling, but it looks like ATI’s providing two different dual-slot coolers to their board partners, one with copper heatpipes and one without. On launch day it looks like most of the board partners are opting for the latter cooler.