AMD Radeon HD 7870 and HD 7850 Review

[siopao1984]

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Introduction / Quick RecapPrior reading before our quick recap: AMD Radeon HD 7800 Series enters the fray just in time to fight GK104 by Nebojsa Novakovic

Glorious shot of the 28nm Pitcain silicon in BGA form factorIn case you've been living under a rock, the HD 7800 'Pitcairn' cards that are released today is sandwiched between Southern Islands flagship HD 7900 'Tahiti' and the entry level HD 7700 'Carpe Verde', price and performance wiseThe HD 7800 series also brings the much vaunted Graphics Card Next architecture to replace the aging VLIW4/VLIW5 designs of previous generationsFeature set wise, the HD 7800 series has the same selling points that we've seen from new AMD cards over the last two months, including improvements in process/power efficiency, flexible multi-monitor configurations and an improved UVD engineSpecifications DumpWe are told that we will not see actual retail cards until 19th March (2 weeks from this review). The consolation is that there will be an impressive array of custom AIB board designs/bloat when it does hit the shops.

Read more: AMD Radeon HD 7870 and HD 7850 Review by VR-Zone.com

[siopao1984]

We received two identical looking cards save for a few stickers differentiating the SKUs. The red and black plastic shroud and blower does look uncannily similar to the HD 7970, but the HD 7870/7850 is shorter at 9.5 inch (~25cm) which should fit in most enclosures.



Like the other Southern Islands GPUs, the Pitcairn brothers has the same display outputs (2 mini-DP, 1 HDMI and 1 DVI-D) for up to six monitor hookup





Back of Card





There is also another HD 7850 reference board design with a shorter PCB and a conventional axial fan which should handle its 130W rated TDP with ease

[siopao1984]

Shot of the card with the heatsink taken off - the HD 7870/7850 uses a conventional 256bit GDDR5 memory design with eight Hynix BGA modules clocked at 1.2GHz



The Pitcairn die is rotated 45 degrees and is slightly depressed below a surrounding metal shim





2 x 6 Pin PCIe power connectors HD 7870 (1 x 6 pin for the HD7850)





Only a single CrossFireX connector is present on the board, which means only up to dual cards (instead of quad) in a multi-GPU rig. The dual bios switch from the HD 69xx/79xx cards is also missing, deterring exotic modding ventures.





CHiL CHL8225G Digital PWM which can drive up to 5 phases and voltage be software controlled





Power Circuitry - 5 phases of Renasas 20658 DrMOS with Pulse PA2080 inductors





Heatsink assembly with the plastic shroud taken off





Sticky thermal pads for the rams





The actual heatpipe heatsink



75mm PWM enabled Foxconn PVB070G12N blower rated at 2A @ 12v and 5000+rpm

[siopao1984]

Overclocking

HD 7850

Unsurprisingly due to its power starved solo 6-pin power connector, we were not able to get any meaningful overclock (only 10 MHz on the core and 50 MHz on the memory) before it would artifact uncontrollably or black out. For the purpose of our benchmarks, we left the clocks at their stock speeds.





HD 7850

Using the excellent MSI Afterburner 2.2.0 Beta 15 which could read and control the CHiL PWM, we bumped the voltage to 1.3v (from 1.21v) and could raise the core clocks as high as 1280 MHz (280 MHz overclock, which is 28%!!!) and memory to 1500 MHz (from 1200 MHz)







Bottleneck Avoiding Test Setup





CPU: Intel Core i7-3960X @ 4817MHz 1.52v
Motherboard: ASUS Rampage IV Extreme (Bios 1005)
Memory: G.Skills RipJawsZ 2133Mhz DDR3 16GB Kit
Power Supply: Antec True Quattro Pro 1200W
Storage: Intel 520 series 250GB SSD
Graphics Cards / Drivers:
8.960 beta drivers:
AMD Reference Radeon HD 7870
AMD Reference Radeon HD 7850
AMD Reference Radeon HD 7970 3GB
Sapphire Radeon HD 7950 OC Edition
ASUS Radeon HD 6970 DirectCU II 2GB
AMD Reference Radeon HD 6990 4GB

295.73 drivers:
MSI N580GTX Lightning Xtreme Edition 3GB (Nvidia 290.36)

[AlbertCruz]

so... can it run Crysis?

2? :P

[siopao1984]

Benchmarks

At 720p resolution, the HD 7870 slots in somewhere in midfield and even beating the HD 7970 when overclocked. The 16CU/1024 shader HD 7850 is too asthmatic to keep up with the big boys, and is left for dead as a result.





Similar story at 1080p - however this time the superior memory bandwidth (which comes into play at higher resolutions) of the Tahiti cards keeps them ahead of the Pitcairns





Nefarious usages (MD5 password cracking) - the superior FP performance of the GCN based cards blows the previous generation away. Although the performance of the VLIW4 based HD 6970 is almost similar to the HD 7870, note that their TDPs are vastly different (175W vs 250W).





Sadly at this point, our GTX 580 and HD 6970 decided to become expensive paperweights (shakes fist at the digital pixies). As soon as we get the cards fixed we will update the following tests:

[siopao1984]

Power Consumption



Predictably due to the 28nm process shrink, AMD has brought their power consumption and efficiencies to new heights. Interestingly, the HD 7870 has the same power draw as the HD 7950, which the latter has more compute units and 384bit GDDR5 memory to keep it ahead in more demanding scenarios.


Conclusion (tl;dr version)

Buy the HD 7870 only if you
1. Are looking for a new card today and have only US$349 to spend
2. Overclock to unlock the vast potential of the card (almost +30%)
3. Want all the niceties like PCIe 3.0, Eyefinity and SteadyVideo
4. Can live with only 2-way CrossFireX
5. Not "upgrading" from AMD Radeon HD 6950 and above OR Nvidia GTX 570 and above
6. Cannot wait for Nvidia's Kepler GK104




Buy the HD 7850 only if you
1. Are looking for a new card today and have only US$249 to spend
2. Don't play games at very high details, resolutions or AA settings and want framerates better than entry level or integrated graphics
3. Don't care much about overclocking
4. Want all the niceties like PCIe 3.0, Eyefinity (considering the lack of horsepower, not advised at all) and SteadyVideo
5. Not "upgrading" from AMD Radeon 6850 and above OR Nvidia GTX560 and above
6. Use it in a HTPC or power conscious setup (single 6 pin PCIe power and ~130W TDP)

[keropi]

Buy the HD 7870 only if you
1. Are looking for a new card today and have only US$349 to spend
2. Overclock to unlock the vast potential of the card (almost +30%)
3. Want all the niceties like PCIe 3.0, Eyefinity and SteadyVideo
4. Can live with only 2-way CrossFireX
5. Not "upgrading" from AMD Radeon HD 6950 and above OR Nvidia GTX 570 and above
6. Cannot wait for Nvidia's Kepler GK104

Satisfied all except 6..

[deathcaex]

so maas hinay ang 7850 compared sa 6850?

[harhar]

Mao na dyud ni...