Priced at well under £100, the ATI HD 4770 presents surprising competition to the respected 4850 graphics cards.
Only last month we found ourselves complimenting both ATI and nVidia for finally restoring some consistency to the naming of their new products.
In theory, the lower the model number, the slower the resulting card should be. After several years of (for all practical purposes) contradictory model names, in recent times ATI and nVidia have striven to provide each fresh launch with a number that signifies its place in the performance hierarchy.
ATI, however, is now running risk of making those waters murkier once more, as its new ATI Radeon HD 4770 graphics chip actually slots in between the 4830 and the 4850. Perhaps what ATI is trying to point out, however, is that, on price alone, the ATI Radeon HD 4770 does indeed come in cheaper then either of those cards. And, given that it produces near-4850 performance, that makes this card something of a stormer.
The RV740 architecture of the ATI Radeon HD 4770 marks it out as the successor to the RV730 of the 4650 and 4670 series.
The 4830 and 4850 use the RV770 architecture, and the HD 4770's lower model name could be explained by the fact that the architecture also comes with a lower number - although to call it this a ATI Radeon HD 4770 when the next two cards up in the series are the ones using the RV770 architecture seems, to us, a little perverse!
The chip itself is, however, rather radical, in that its been produced on a 40nm manufacturing process, making it considerably more compact and efficient then the 55nm dies of the 4830 and 4850.
The eventual success of the ATI Radeon HD 4770 won't necessarily be apparent from the specifications. That's because, in terms of raw figures, the ATI Radeon HD 4770 is good in places... but also a touch deficient. The deficiency in the ATI Radeon HD 4770 is mainly the memory interface - a quite horrible 128-bit bus, that would appear to hold it back when it tries to compete with the 256-bit interfaces of the 4830/4850.
ATI, however, has given it a significant advantage elsewhere - whereas the RV770s stick with GDDR3 memory, the ATI Radeon HD 4770 gets juicy GDDR5 modules.
These allow it to take that slightly underdone memory clock of 800MHz (the Sapphire 4830 and Gigabyte 4850, by comparison, have memory clocks of 900MHz and 960MHz) and, by quadrupling it (GDDR3 would only double the figure)), produce an effective speed of 3600MHz - almost twice that of even the respected 4850.
The core clock speed is a touch faster too, hitting 750MHz in comparison with the figures of 575MHz and 625MHz offered by the 4830 and 4850 in our graphics cards chart.
We can see further room for improvement too. This first edition of the ATI Radeon HD 4770 essentially takes the standard 4770 and attaches HIS' badge to it. But we're sure there'll be future rejigs that push those specifications further still.
The ATI Radeon HD 4770 card itself is fairly quiet in use, and requires only one 6-pin connector. CrossFireX is supported and, given the low pricing, we could see this being a first choice for many a double or triple graphics card system.
As for performance, you don't need to delve much into the figures to see that it runs the ATI Radeon HD 4850 pretty close. Far Cry 2 could hit 63 frames per second, even at the HD-plus-res of 1920x1200. Only at times of high load - essentially the top resolutions, and Crysis - does the 4850 pull out any real lead.
With Crysis Warhead, for example, we recorded 27fps at 1280x800, dropping to 15fps at 1920x1200. So even here, the 4770 holds on fairly well, despite having fewer stream processors.
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