Recently, a serious struggle has developed between AMD and NVIDIA for leadership in the class of high-performance adapters. More and more new models entered the market, which became leaders in performance for a fairly short time. The increase in performance was mainly due to an increase in the number of transistors in the graphics core and an increase in its nominal frequency. No fundamental changes were introduced into the structure of the graphics core, not to mention the transition to a new thinner technical process. All this resulted in high consumption and, as a consequence, difficulty with cooling. To a greater extent, AMD faced these difficulties. The HD 7970 video adapters were hotter and consumed more power than their direct competitor, the GeForce GTX 680 adapters. Perhaps that is why AMD hesitated for a long time to release a dual-processor model. The standard model Radeon HD 7990 appeared with a significant delay after a number of partner companies offered the buyer their versions of the HD 7990. The model has become a real "monster" with a huge level of power consumption. However, only this model could compete with the previously released GTX 690 and GTX TITAN. Both manufacturers soon updated their graphics card lines. Moreover, the user did not see any fundamental changes in the structure of the graphics core. Almost the entire new line of adapters from both manufacturers consisted of renamed old models, with the exception of top solutions. The new flagships became even hotter and consumed even more power. Now the power consumption bar has risen to 300 W and this is for a single-processor video card (Radeon R9 290X and GeForce GTX 780 Ti). Due to the high power consumption, the appearance of dual-processor video cards based on top-end GPUs looked very vague. Nevertheless, both companies decided to release such models. NVIDIA recently introduced a dual-GPU GK110 - the GeForce GTX TITAN Z.
At the same time, NVIDIA engineers had to compromise by lowering the nominal frequency of the GPU. Despite the reduction in the nominal frequency of the GPU, the cooling system of the video adapter occupies three expansion slots. At that time, AMD engineers were working on a new dual-processor video adapter Radeon R9 295X2, which replaced the Radeon HD 7990. What happened to the company's engineers, we learn from this review.
Specifications and packaging
Despite the fact that the Hawaii XT GPU turned out to be very hot and has a fairly high power consumption, the engineers still managed to fit two such processors on the same PCB. However, they did not reduce the nominal frequency. The main technical characteristics of the video adapter Radeon R9 295X2 are given in the table.
As you can see from the technical specifications, we have a full-fledged array of two Radeon R9 290X placed on one board.
The video adapter Radeon R9 295X2 came for testing packed in an aluminum case with combination locks, on the side panels of which there is an outline image of the adapter.
Design
The company's engineers solved the problem of cooling two high-TDP GPUs located on one board using a liquid cooling system. It is thanks to her that I did not have to reduce the nominal frequency of the GPU and at the same time keep the overall dimensions of the adapter within more or less reasonable limits.
On the front side, the adapter is closed with a metal casing, in the center of which there is a 90 mm fan, which has a red LED backlight.
The adapter uses a closed-loop liquid cooling system ASETEK with a single-section radiator, for which one fan with a diameter of 120 mm is used.
Its maximum rotational speed can reach 900 rpm, making it virtually silent. The overall dimensions of the radiator with the installed radiator are 120 x 152.5 x 64. The length of the connecting pipes in the cooling system is 380 mm.
By unscrewing the fastening screws located on the side panels of the video card, you can remove the metal casing together with the fan attached to it.
Under the casing there are two water blocks with the ASETEK logo.
The PCB is completely enclosed by a large metal frame with a copper heatsink and small fins all over the surface. A copper radiator is used to cool the power elements of the power supply subsystem. The radiator is located in the middle just below the fan. The metal frame is used to cool the video memory chips and the PCI-E bus switch.
The back side of the PCB is also almost completely covered with a metal frame.
It also acts as a heatsink for video memory chips, and also serves as a reinforcing plate.
On the side surface of the metal casing there is an inscription "Radeon" with LED backlighting.
Printed circuit board
Removing the metal frames reveals a PCB with probably the most complex wiring to date. The video adapter Radeon R9 295X2 uses a 14-layer printed circuit board with a very dense arrangement of elements. The power subsystem elements are located in the middle.
The engineers had to reduce the number of power phases. 6 power phases are used to power each "half" of the adapter. Of these, 4 power the GPU. The total number of power phases for the video adapter is 12. The power phases are controlled by two NCP81022 controllers.
The declared power consumption of the adapter is 500 W. In this regard, it is not clear why only two 8-pin connectors are installed for additional power supply, which, according to the specification, can transmit up to 150 watts.
Another 75W can come through the PCI-E slot. Thus, they all together, according to the specification, can transfer up to 375 watts to the video card. But the company's engineers do not see a problem in significantly exceeding the established norms. When installing such a video card, the user should be very careful when choosing a power supply. The engineers do not indicate the rated power of the power supply, but only give the value of the current consumption, which is 50 A.
GPUs are located to the left and right of the power subsystem. A PEX 8747 switch manufactured by PLX Technology is used to communicate between the two GPUs.
Each GPU has its own set of 4 GB video memory, recruited with 16 microcircuits, which are located 8 pieces on each side of the printed circuit board. Thus, there are 16 microcircuits on the front side of the printed circuit board and 16 more on the back side. Due to the peculiarities of the construction of the Cross Fire X array, the amount of video memory is not added. SK Hynix microcircuits marked H5GC4H24MFR are used as video memory.
GPUs run at 1018 MHz. Of course, such an increase cannot be called significant, but due to the presence of a liquid cooling system, the nominal frequency should not decrease due to overheating. This should have a positive effect on performance, as a result of which we can assume that the Radeon R9 295X2 will be faster than two standard Radeon R9 290X combined into an array.
Like the Radeon R9 290X, the video adapter is equipped with two BIOS versions, the choice between which is carried out using a microswitch.
In practice, it turned out that the two BIOS versions are no different from each other.
To display the image, the video card is equipped with five connectors (four mini-DisplayPorts and one dual-link DVI).
Power consumption temperature and overclocking potential
There are two fans in the cooling system of the Radeon R9 295X2 video card. One is located directly on the adapter and cools the elements on the PCB.The second is installed on the radiator of the liquid cooling system. However, unlike video cards with air cooling systems, the user does not have the ability to adjust the rotational speed of the installed fans. The rotation speed of the fans on the video adapter and on the heatsink is regulated only in automatic mode. It depends on the temperature of the components on the board and the sensors located in the water blocks.
When testing the video adapter on an open bench, its temperature did not exceed 65 degrees. After installation in a closed case with good ventilation, the adapter temperature did not exceed 70 degrees. Many will immediately say that this is an excellent result, which is incomparable with the result of the Radeon R9 290X (94 degrees), but you should pay attention to the fact that the maximum temperature limit for the Radeon R9 295X2 is set by the manufacturer at 75 degrees. In addition, it is worth considering the fact that at the maximum load on the graphics processors, the elements in the power subsystem heated up to 105 degrees. Considering all of the above, a video card simply needs a large case with well-organized cooling of internal components. In terms of power consumption, the test system with the Radeon R9 295X2 consumed 680 watts. This is 53W less than the power consumption of the test system with two Radeon R9 290X and 70W more than with two GTX 780 Ti.
When evaluating the overclocking potential of the adapter, its nominal frequencies were increased to 1100 MHz for graphics processors and up to 6900 MHz for video memory.
Testing
Radeon R9 295X2 video adapter was tested as part of the following system
Central processor Intel Core i7-4960X 3600 MHz / L2-6x256 Kb / DMI LGA2011 Box (BX80633I74960X);
Asus P9X79 LE / C / SI s2011 ATX bulk motherboard;
RAM Geil DDR3 2x8192 Mb PC3-12800 1600 MHz (2 sets);
Silicon Power Slim S60 480 Gb SSD 2.5 "SATAIII hard drive;
Chieftec Navitas GPM-1250C 1250W PSU.
The adapter was tested at a resolution of 3840 x 2160 pixels and maximum graphics quality. Video adapters were taken as rivals for the tested model:
AMD Radeon R9 290X;
AMD Radeon HD7990;
NVIDIA GeForce GTX 780 Ti;
Array of two Radeon R9 290X;
Array of two GeForce GTX 780;
Array of two GeForce GTX 780 Ti.
When tested in gaming applications, all video cards worked at nominal frequencies.
The test results are presented in the form of a table.
conclusions
The Radeon R9 295X2 video adapter is by far the most powerful adapter to date. Its performance level is slightly higher than the array of two Radeon R9 290X, mainly due to better cooling. Lower power consumption than an array of two Radeon R9 290X is achieved through a dedicated selection of GPUs that are capable of stable operation at lower voltages. However, you shouldn't expect the graphics card to be great for overclocking thanks to the liquid cooling system. In my opinion, this is not the case. The video card has an underestimated maximum temperature limit - 75 degrees versus 94 degrees for the Radeon R9 290X. The video card also has a "weak" power supply subsystem. At maximum load, the temperature of the elements rises to 105 degrees. Under the same conditions, the temperature of the power supply subsystem of the MSI Radeon R9 290X LIGHTING video adapter did not exceed 67. It is the power subsystem and the temperature limit that, in my opinion, are the limiting factors when overclocking the adapter. Perhaps there will be models from partner companies with a reinforced power subsystem and a higher temperature limit, which will allow the adapter to show a higher overclocking potential, but so far there are no such models.
As for the cost of the adapter, it is noticeably higher than that of an array of two Radeon R9 290X and is very close to the cost of two GeForce GTX 780 Ti, so how much such an overpayment is justified, let everyone decide for himself.
