Manufacturer: AMD UK Price (as reviewed): TBC (estimated £200 inc VAT) US Price (as reviewed): TBC (estimated $249 ex. tax)
Despite the HD 7800 series’ mid-range claims, the HD 7870 2GB is a pricey card thanks to what looks to be a £275 price tag. That still leaves a whopping £150 price gap in AMD’s line-up down to the £130 HD 7770 1GB and it’s into this gap that the HD 7850 2GB fits.
Its 212mm² 2.8 billion transistor Pitcairn Pro 28nm GPU is very similar to that of the HD 7870 2GB, with only clock speeds and CU count differing between the two. This means that Pitcairn Pro boasts both the same dual front-end layout as the high end Tahiti GPUs of the HD 7900 series and the full set of eight render back-end units for a total of 32 ROPs.
Click to enlarge - This is AMD's stock version of the HD 7850 2GB, but most board partners will be using their own coolers and PCBs
The memory interface is also the same as the HD 7870 2GB, with a quartet of 64-bit dual channel memory controllers making for a 256-bit memory interface connected to 2GB of GDDR5. As both cards sport the same memory frequency of 1,200MHz (4.8GHz effective), this means they share a peak memory bandwidth of 153.6GB/sec.
With the same front-end and memory layout as the HD 7870 2GB you’d be forgiven for thinking there’s little between the two GPUs. Sadly, AMD has put the brakes on with the HD 7850 2GB when it comes to both CU count and core frequency. While the HD 7870 2GB sports 20 compute units (1,280 stream processors) running at 1GHz, the HD 7850 2GB packs 16 compute units (1,024 stream processors) running at 860MHz.
Click to enlarge - Pitcairn Pro offers four fewer CUs and a lower core frequency, but is otherwise the same as the HD 7870 2GB's Pitcairn XT
Just as the HD 7870 2GB offered almost double the resources of the HD 7770 1GB, the HD 7850 2GB offers double the resources of the HD 7750 2GB; twice the stream processors, twice the memory, twice the front-end and twice the ROP count.
And just as with the HD 7870 2GB, the HD 7850 2GB also benefits from all the AMD gubbins we’re coming to expect from 7-series GPUs. That means support for up to six-display Eyefinity from a single card, PCI-E 3.0, two-card CrossFire and the excellent ZeroCore Power Technology.
However, we’re in something of an odd situation for this review, as AMD hasn’t actually furnished us with a stock review sample. Instead we received an HD 7850 2GB GPU fitted into a stock HD 7870 2GB PCB, albeit with just a single 6-pin PCI-E power connector. Our understanding is that stock cards will be a rarity, with almost every board partner using its own custom PCB and cooling layout. With card availability still two weeks out, this means we’ve been unable to perform any kind of meaningful power or thermal testing on a genuine HD 7850 2GB (our sample returned identical results as the stock HD 7870 2GB).
Click to enlarge - AMD sent us an HD 7850 2GB in an HD 7870 2GB PCB
With so much variety between manufacturers there’s likely to be little uniformity other than the need for a single 6-pin PCI-E power connector. AMD has told us that some boards will measure less than 200mm, which would certainly qualify the HD 7850 2GB as something of a pocket rocket card ideal for mini-ITX systems.
Pricing is also a little uncertain, but around £200 seems to be where most pre-orders are hitting. We’ll publish an update once we get our hands on a genuine HD 7850 2GB and once retail pricing becomes clearer.
Graphics processor AMD Radeon HD 7850 2GB, 8,60MHz