Gigabyte HD 7770 OC full review

Although our higher end graphics card chart is filling up nicely with new models, the more mainstream pricing area south of the £150 mark remains barren territory for 2012’s latest pixel-punchers. 

So it’s welcome to see the emergence of this Gigabyte HD 7770 OC, the larger brother of the AMD Radeon HD 7750 currently filling the runner-up slot in our sub-£150 chart. Read more graphics cards reviews.

We say larger brother, but this Gigabyte HD 7770 OC version of the AMD Radeon HD 7770 isn’t actually as long as you might think. While AMD’s reference board measures a 210mm, this resized Gigabyte version only stretches to 198mm. And it also boasts an improved cooling system. 

Indeed, the Gigabyte HD 7770 OC barely even registered on our sound meter, a testament to the high-quality job that Gigabyte has done on the reference design in a very short space of time.

But what of the AMD Radeon HD 7770 itself? Well, like the 7750, it fits into the Cape Verde line-up – all of AMD’s new cards are named after ‘Southern Islands’. 

And just like the other 2012 models, it’s crafted using AMD’s more efficient 28nm manufacturing process. In most respects, the 7770 is like a slightly tweaked version of the 7750. Like that card, it offers a 128-bit memory interface and 1GB of GDDR5 RAM. 

That’s not a patch on the 2 or 3GB memory offered by the £250+ cards, but no less than is found on the other cards at the 7770’s price point. The memory interface is slightly disappointing, but as the figures will show, the 7770 is still capable of some solid game framerates.  

The standard 7770 also shares the 7750’s memory clock of 1125MHz (4.5GHz DDR effective), although Gigabyte’s overclocked HD 7770 OC pushes this to 1250MHz (or 5GHz, DDR effective).

That means that, in spite of the meagre 128-bit interface, the Gigabyte HD 7770 OC generates a memory bandwidth figure of 80GBps – noticeably higher than the standard 7750’s 72GBps, but still not particularly impressive.  

The Gigabyte HD 7770 OC does brighten up when it comes to the core-clock speed. The default figure of 1GHz (itself 200MHz up on the 7750’s figure) is boosted, again by Gigabyte, to an even more emphatic 1100MHz. 

And the Gigabyte HD 7770 OC also pushes up the number of texture units from 32 (in the case of the 7750) to 40. This allows the card to offer a texture fill-rate of 44GTps – a huge improvement on the 7750’s 25.6GTps.

Add another increase in the number of stream processors, from 512 (in the 7750) to 640, and you have a very promising little card that could offer quite an improvement in gaming for that £25 price difference.

Gigabyte HD 7770 OC: Performance

In real-world testing, the Gigabyte HD 7770 OC proved to be a good few notches up on the 7750. In BattleForge, the 7770 scored 40.5 and 36.0fps at resolutions of 1680x1050 and 1900x1200 respectively. This compared with 31.3 and 27.5fps in the case of the 7750 – and those differences of 8-9fps could prove significant in allowing you to play games at a decent resolution. 

The differences weren’t as great in Crysis 2, where the figures were quite low to start with. Here the 7770 scored 25.1 and 23.9fps, as opposed to 19.9 and 18.2fps in the case of the 7750. 

Stalker: Call of Pripyat saw the Gigabyte HD 7770 OC return to lead in the region of 7-8fps, with its figures of 37.3 and 35.8fps an impressive winner over the 7750’s 30.8 and 27.3fps. 

However, it’s also worth noting that the older AMD Radeon HD 6850 – still available for a similar price to the 7770 OC – recorded slightly higher figures than the 7770. These differences never amounted to more than a couple of frames per second, but the 6850 was consistently but marginally faster.


Gigabyte HD 7770 OC: Specs

  • AMD Radeon HD 7770
  • 1GB GDDR5
  • 1100MHz core clock
  • 1250MHz memory clock (5000MHz DDR effective)
  • 400MHz RAMDAC
  • 128-bit memory interface
  • 640 stream processors
  • 40 texture units
  • 16 ROP units
  • PCI-E interface
  • DirectX 11.1
  • 1 x DVI, 1 x HDMI, 2 x Mini-DP
  • 6-pin connector
  • 3-year warranty