Table of Contents
With a price tag of just $100, the Sapphire HD 6750 is a low to mid-range video card offering performance on a budget. Time to stress and strip the card to see how it compares to two of its bigger brothers.
Features & Specifications
|Core Clock||700 MHz|
|Memory Clock||1000 MHz (4Gb/s)|
|Memory Bandwidth||64 GB/s|
|Shader Operations||504000 MOperations/s|
|Pixel Fill Rate||11200 MPixels/s|
|Texture Fill Rate||25200 MTexels/s|
|Memory Size/Type||1024 MB GDDR5|
|Memory Bus Width||128 bit|
- AMD Eyefinity – AMD Eyefinity technology allows the card to drive up to three displays.
- AMD CrossFireX™ Multi-GPU Technology – AMD CrossFireX technology supports up to four graphics cards in a single system.
- AMD HD3D Technology – High Definition Stereoscopic 3D is a technique that presents 2D images (movies, games, photos) in a format that creates the illusion of three-dimensional depth when using compatible 3D displays / glasses / software.
- HDMI 1.4a – HDMI 1.4a builds on previous generations of HDMI connectivity with support for Deep Color, 7.1 High Bitrate Audio, and 3D Stereoscopic support.
- Microsoft DirectX® 11 – New features in DirectX®11 include Hardware Tesselation, HDR Texture Compression, Multi-threading support and DirectCompute
- OpenGL® 4.1 – Supports the latest OpenGL API (Application Programming Interface) to accelerate performance of applications outside of DirectX®, i.e. Adobe Autodesk 2D/3D graphic design.
- Shader Model 5.0 – Supports the latest Shader Model 5.0 feature set including VTF (Vertex Texture Fetch) which is a key feature used extensively in many of the games that ship today.
- AMD Catalyst Control Center™
- Accelerated Video Transcoding – Massively parallel architecture and support for common shader transcoding instructions accelerates video encoding / transcoding beyond what is possible with only a CPU.
- Dolby® TrueHD and DTSHD Master Audio™ Support – Support for copy protected, high bandwidth, 7.1 channel surround sound over HDMI.
- 2nd Generation TeraScale Engine – Supports more than 4 teraFLOPS of compute power.
- Physics Processing Support – Accelerates the performance of Fluid Dynamics, Cloth Simulation, Soft or Rigid Body Dynamics, Universal Collision Detection, Hair Simulation and Finite Element Analysis.
- AMD PowerPlay™ – Manage power efficiency and performance; AMD PowerPlay TM power management technology delivers high performance features when needed and conserves power when the demand on the graphics processor is low
- AMD Advanced Parallel Processing Technology – Accelerate the most demanding applications by offloading parallel data compute tasks from the CPU to GPU, dividing the tasks as evenly as possible for improved system performance and reliability.
- AMD App Acceleration – Use the power of your AMD Radeon™ GPU to speed up everyday applications like your web browser and Microsoft Office 2010 using AMD App Acceleration.
The front of the box highlights a few features of the HD 6750, lists the amount of vRAM, and showcases a “CG babe” for the consumer. On the back of the box, the features highlighted on the front are described in more detail and in layman’s terms on the right, and Sapphire’s marketing spiel and box contents are listed on the left. Personally I’d like to see a picture of the card and/or the physical dimensions, such as length and number of PCI slots needed, listed on the box. The contents include a driver CD, installation manual, DVI to VGA adapter, Molex to 6-pin adapter, and the HD 6750 itself. All of these are inside of a cardboard box with the GPU in a anti-static, bubble wrap bag. There’s not a lot of padding, but everything arrived safely.
The HD 6750 isn’t a bad looking card, in my opinion. It is definitely not gaudy like some of the non-reference designs seen today. The heatsink shroud has smooth edges that curve down all sides of the heatsink. It’s also a very compact card, coming in at 7.25″ in length, and it takes up two PCIe slots like most discrete GPUs nowadays. The card requires only one 6-pin PCIe power connector, so it’s not a power hungry card at all. The video outputs include DisplayPort, HDMI, and DVI. The DisplayPort was expected for Eyefinity support, the HDMI socket allows connection to a HDTV, and DVI is provided for the majority of PC monitors. The included DVI to VGA adapter can be used to ensure compatibility with older monitors too.
After removing the heatsink and taking a closer look, the first thing I noticed was that there was quite a lot of TIM used, but at least it’s not dried out and flaky like factory TIM I’ve seen on multiple cards before. Next, I took a close look at the GPU die and RAM chips to get the numbers printed on them. The number on the GPU, 215-0754009, verifies this is a Juniper like those in the HD 5750/5770 cards, and that the HD 6750 is a rebranded HD 5750. The RAM chips are Hynix H5GQ2H24MFR-T2C which are rated for 2500 MHz effective (1250 MHz actual), so it should be possible to increase the RAM frequency from 1000 MHz to 1250 MHz without a problem.
So, we basically have a HD 5750 with a couple of noteworthy differences: HDMI 1.4a support and UVD3 video decoding. However, the only features of HDMI 1.4a that are supported are those associated with HDMI 3D, so no 2160p resolutions through HDMI.
I decided to keep everything, other than the GPUs, at stock settings so I would be confident that any instabilities I encountered were due to the GPUs. My complete system is as follows:
- CPU: Intel Core i5 680 @ 3.6 GHz
- Motherboard: Gigabyte GA-P55A-UD7
- RAM: 2 x 2 GB G.Skill ECO DDR3-1600 @ 1333 MHz
- GPUs: AMD HD 6850 (ES), Sapphire HD 6750, MSI R5770 Hawk
- Storage: 50 GB OCZ Vertex 2 SSD
- Power Supply: Corsair VX550W
- Operating System: Windows 7 x64
- Drivers: Catalyst 11.5
- Fluke 52-II Digital Thermometer
- P4400 Kill-A-Watt
For performance testing I used both synthetic tests and game tests. The synthetic tests consisted of 3DMark06, 3DMark Vantage, and 3DMark11. The 3DMark software was run using default “Performance” settings. The game tests used were Alien vs Predator, S.T.A.L.K.E.R., HAWX 2, and Lost Planet 2. These tests were ran at a resolution of 1920 x 1200 with Vsync disabled; DX11 was used where applicable and with any other settings were left at their default values. I tested the HD 6750 at stock and overclocked settings, HD 5770 at stock, HD 6850 at stock, and HD 6750 + HD 5770 CrossFireX at the HD 6750’s overclocked settings.
For cooling, I used a Fluke 52-II and RealTemp v3.60 for measuring temperatures. The Fluke’s K-Type probe was set up so that is was ~1″ from the HD 6750’s intake fan to record ambient temperatures, which stayed between 25-26 °C throughout the tests. The only exception was the CrossFireX setup. I used the HD 6750 as the top card and recorded ambient temperature from between the two cards since that’s where the HD 6750 was pulling air from. Ambient during CrossFireX testing was ~2 °C higher, so 27-28 °C. RealTemp v3.60 was opened before running any of the tests and remained open during the tests so that it could record the maximum GPU core temperature during the tests. The temperatures of the HD 6750 were recorded at overclocked settings to show the max temps with fan set to 100%.
For system power consumption, I recorded the peak wattage reading according to a P4400 Kill-A-Watt during each test. I realize that the Kill-A-Watt is a ~$17 meter, so the readings probably aren’t as accurate as those that could be obtained with more specialist equipment, but it should provide a fair gauge of power consumption differences between setups and settings. The power consumption when using the HD 6750 was recorded while at overclocked settings to show the overall max wattage.
I overclocked the HD 6750 using Catalyst Control Center, but I did check Sapphire’s own TRIXX utility and MSI Afterburner. Sapphire TRIXX didn’t allow any adjustment, but Catalyst Control Center and MSI Afterburner allowed up to 870/1430 (core/vRAM). Core voltage adjustment isn’t allowed on any of the utilities, so that remained at the stock voltage of 1.1v at 3D clocks. I first tested the vRAM at Hynix’s rated spec of 1250 MHz which is 250 MHz more than default speed for this HD 6750. The card passed benchmarks at 1250 MHz easily, but I couldn’t get it past 1300 MHz. The core clock was able to pass all benchmarks at the maximum allowed (870 MHz), which is a 24.3% overclock from the default speed of 700 MHz. I’m not sure how high the core is able to go since I reached the software limit during testing: there may well be more headroom left in this card.
I used five different GPU setups during the performance testing: HD 6750 at stock clocks, HD 6750 overclocked to 870/1300 (core/vRAM), HD 5770 at stock clocks, HD 6850 at stock clocks, and HD 6750 + HD 5770 CrossFireX at 870/1300 (core/vRAM). There’s nothing out of the norm in the synthetic testing. Everything falls in line as expected with the overclocked HD 6750 pretty much matching a stock HD 5770.
The results of the game tests turned out pretty well for the HD 6750 considering the high (1920 x 1200) resolution being used. STALKER and HAWX 2 are definitely within playable frames per second, Alien vs Predator comes close, but all the cards struggled in Lost Planet 2. Something that really stands out to me are the Lost Planet 2 and HAWX 2 CrossFireX results, or lack thereof. Those two tests just didn’t gain anything from CrossFireX, and the HD 6850 did better than CrossFireX by quite a lot.
Next, a look at how the HD 6750 fared in the performance per dollar category. In the synthetic tests, the HD 6750 matched or beat the HD 5770 and HD 6850 in 3DMark11 and 3DMark06. However, the HD5770 edged out the HD 6750 in Vantage performance per dollar. The game tests show that the HD 6750 fall a little behind the other two cards in performance per dollar in all the tests except STALKER Night. Once the HD 6750 is overclocked, it’s performance per dollar increases quite a bit. This is because of the very good overclockability of the core, which maxed out the software used. So, the HD5770 looks the be the best performance per dollar GPU among the cards at stock clocks, but an overclocked HD 6750 is a great candidate for performance on a budget.
Before I get into the cooling performance, I’d like to take a closer look at the heatsink. The heatsink is definitely not a symmetrical design. The GPU die makes contact off-center, but the fan remains centered over the heatsink. I contemplated why the heatsink was designed this way, then it hit me after a few minutes of thinking. I noticed that the heatsink was offset in a way that more of it was situated above the RAM chips, it is offset toward the top right of the card. What this does is allow the fan to blow over the RAM chips better than if it was centered. I mentioned earlier that the shroud was curved downward on the edges, but that’s not just for good looks. It directs the airflow downward towards the PCB and prevents air from escaping out of the sides before it hits the heatsink and RAM chips. So, there was some thought put into this heatsink; Sapphire didn’t just throw a heatsink that was “just enough” onto this GPU.
For the results below, the HD 6750 temperatures were recorded while running overclocked to 870/1300 (core/vRAM) and using the stock cooler shown above running at 100%. The HD 5770 uses MSI’s Twin Frozr II cooler and results were recorded with the fan on auto. The HD 6850 has a Prolimatech MK-13 cooling it with a San Ace 109R1212H101 fan at its lowest possible speed using a Lamptron FC5V2 fan controller. So, we have a mix of high-end, mid-range, and low end air coolers. The HD 6750’s stock cooler did very well, only topping out at 62 °C while running FurMark.
All the cards I tested are within 10-20 W of each other in system power consumption. The overclocked HD 6750 uses a little less wattage than the HD 5770, even though performance is about the same. Something I noticed that can be related back to the performance chart, is the power consumption of the CrossFireX setup in Lost Planet 2 and HAWX 2. In the performance chart, those two tests didn’t see a benefit from CrossFireX. Plus, in the power consumption chart below, those two tests didn’t see much more power draw while running CrossFireX either. It’s almost like one of the cards isn’t being used at all, and the minor power consumption increase is just from having an additional card idling. If you notice the difference in idle power consumption between non-CrossFireX and CrossFireX, it’s around 15-20 W, and the difference in loaded power draw during Lost Planet 2 and HAWX 2 is around 15-35 W. So, it seems to me that one card wasn’t being used much, if at all, during those two tests.
Overall, I believe the HD 6750 serves its purpose well. It performed better than expected at 1920×1200, and will only perform better at more mainstream resolutions such as 720p, 1680 x 1050, and 1080p. When overclocked, the HD 6750 can reach HD 6770/5770 performance while using less power. Although the HD 6750 isn’t the best performance per dollar GPU at stock clocks, its ability to overclock well helps make up the slack in that department. The stock cooler looked pretty weak at first glance, but it ended up doing quite well during all the tests while the GPU was overclocked. The cooler was even designed to better cool the vRAM by being offset more towards those chips.
The HD 6750 seems like a very versatile card as well. It’s rather small at only 7.25″ in length, which will help it fit into a variety of small form factor cases with room to spare. There’s a connector for any type of current display, including a full sized HDMI port. So, no need to worry about and keep up with multiple adapters. The HD 6750 has also been upgraded from the HD 5750 in that it now supports 3D through HDMI, and has an upgraded video decoder for HTPC purposes.
With a price tag just above $100, I don’t believe you can get a better deal for a new GPU as feature-rich as the HD 6750. The HD 6750 does everything it was intended to do and its versatility would be hard to match.
– Matt T. Green (MattNo5ss)