LAB501

Clash of the Titans VGA 2014 – ASUS Geforce GTX 780 Ti DirectCU II vs ASUS Radeon R9 290X DirectCU II

Cooling

In past articles I have criticized the design choices and also the aesthetics of the coolers that ASUS employs for its DirectCU II series. And although stock coolers are not the focus of such articles, I certainly wasn’t pleased to see ASUS making use of a HDT heat sink base, nor by the generally oversized dimensions of the cooler. The cards we will be benching today still employ a HDT base for their coolers, but at least the design has improved, now the coolers are slimmer and they sport larger fans, of which one is based on the CoolTech technology.

Construction quality is good, we have nickel plated fins and the 5 heatpipes are placed without any spacing between them, which in terms of heat transfer constitutes a superior solution to a traditional HDT base. In the future I would like to see a solid copper base for a plus of performance on the DC2 series.

We are dealing with an evolution in this chapter, the performance is acceptable, as you can see in the tests below. I tried to generate equal conditions for the tests, so we used the same voltage in load for both cards. The R9 290X bios is for LN2 (where I’ve used a different one I’ve specified), with the same voltage as standard (1.15 V and disabled 2D), and for the 780Ti I modified the BIOS to 1.15V under load, boost power off and limit to 200% (combined with a higher set TDP), changes that were sufficient to maintain a fixed frequency at the highest voltages.

We have a lower temperature for the GTX 780 Ti caused by the larger DIE, while power consumption is about 70 Watts higher for the GTX 780 Ti as well.
In this chapter we did overclocking tests with stock cooling and 1.15V under load, measuring also the power consumption.

ASUS Geforce GTX 780 Ti DC2

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, auto RPM – 58 oC

ti_test_1_1.15v_21amb_auto rpm

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, max RPM – 49 oC

ti_test_2_1.15v_21amb_max rpm

MAX OC

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, max RPM – 52 oC/1251 MHz/508 W

508 watt max_166 idle_1250mhz

ASUS Radeon R9 290X DC2

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, auto RPM – 69 oC

1.15v load_21c_auto

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, auto RPM (original BIOS) – 68 oC

1.15v load_21c_auto_orig bios

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, max RPM – 61 oC

1.15v load_21c_max rpm

MAX OC

3DMark 2011 X, 1.15v load (MM), 21 oC ambient, stock cooling, max RPM – 70 oC/1120MHz/435 W

1.15v load_21c_max rpm_1120_435watt load_240 idle

GPU frequency is stable, there are no issues with frequency drop, RPM scaling is good as well and the VRM temperature reiamns in normal limits. In regard to VRM cooling, I have to point out some design issues and heat transfer problems: the positioning of mosfets does not allow for direct heat sink contact which would improve cooling, and while the thick thermal pad does a good job, it’s far from brilliant. Anyway, not a negative point since the voltage regulator is very robust, but at this level even minor design imperfections tend to stand out.

Once again GTX580 DC2 is the etalon, and here you can see that it maximizes VRM heat transfer through direct contact of the heat sink with the mosfets (just between you and me, that overbuilt VRM doesn’t need any cooling). As for negative aspects, I can only mention the HDT base again, and also a better placing of the VRM components would be desirable.

With the R9 290X I did two more tests, just to see how the cooling behaves in game environments and what is the highest frequency achievable at 1.4 Volts with the stock heat sink. Ambient temperature was 23 oC and fans set on auto for the first test, while for the overclocking test fans were set to their maximum RPM. The game used was Tomb Raider, 30 minutes of continuos play.

MAX OC: 1.4v GPU Tweak – 1230MHz/530 W

1.4v soft_21c_530watt_1230mhz_stoc cooler max rpm

Tomb Raider: 30 min, auto rpm – 73 oC

tomb_max_23c_auto rpm_orig bios

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As a positive, we have the presence of backplate, useful in preventing PCB bending and protecting very fragile SMD components. Another positive aspect is the lateral reinforcement of the VGA and the design precision of the cooling system, which keeps the PCB perfectly straight.

The HDT bases are superbly flat, a fact which led to good TIM prints. I can not take off the heat sink without partially destroying the print, because the large DIE surface makes the required detaching pressure quite high, and we risk damaging the BGA balls.

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