AMD ATI Radeon 3850 & 3870 review - Page 8 - Thermals, Wattage and noise levels

Power consumption

It's time to do some actual testing with these cards. We'll start off by showing you some tests we have done on overall power consumption of the PC. Power consumption is a big thing, and I'm thrilled to see what AMD has achieved here.

Looking at it from a performance versus wattage point of view, the power consumption is really good with the new 55nm products. Our test system is a Core 2 Duo X6800 Extreme Processor, the nForce 680i SLI mainboard, a passive water-cooling solution on the CPU, 2GB memory, DVD-ROM and WD Raptor drive. Have a look:

Observe closely the difference between the 2900 and the 3870. Shocking as performance is nearly equal while wattage dropped over a 100 Watts. A big thumbs up to AMD here, that's just brilliant.

The methodology is simple: we look at the peak wattage during our benchmark session to verify power consumption. It's a good load test as both GPU and CPU are utilized really hard here. Please do understand that you are not looking at the power consumption of the graphics card, but the consumption of the entire PC.

In my view the Radeon HD 38xx series require you to have a 450 Watt power supply unit at minimum if you use it in a high-end system, and I think that's barely on the safe side. Also recommended is 28 AMP's on the 12 volts rails for stable power distribution (on a single card configuration)

Notice that the card uses one 6-pin power connector and not another one 8-pin connector.

If you have dough to spend and opt the guru path of righteousness by doubling up towards two/three/four cards in your system -> CrossfireX, then you should end up with a 800 Watt or better PSU with a 45 AMPs 12 Volts rail. Definitely check out this PSU review, please.

There are many good PSU's out there, please have a look at our many PSU reviews as we have loads of recommended PSU's for you to check out in there. What would happen if your PSU can't cope with the load?:

• bad 3D performance
• crashing games
• spontaneous reset or imminent shutdown of the PC
• freezes during gameplay
• PSU overload can cause it to break down

The Series 3000 thermal envelope

Let's have a look at the temperatures these cards produce. We measured at a room temperature of 21-22 Degrees C, look at idle temperature and then load the GPU 100% for a couple of minutes and measure the temperature once a second and follow the temperature delta.

	HIS Radeon HD 3850 256MB

Due to the lower clock the 3850 series have a single slot cooler. This HIS model has the reference cooler, yet the ICEQ version will be available later this month already.  Much like the 8800 GT from NVIDIA we notice that AMD is also increasing the thermal levels. It seems that under load 90 Degrees C is now the upper plafond [Ant - Ceiling][Hilbert - Come on man, be a bit French]. Quite hot to be honest, yet should be considered to be a normal operating temperature.

Update - We discovered what we think is a bug in the RV3850 samples. We where curious about the high (90c) temperatures these cards produce (very likely a reference issue thus all boards have this high temperature). When we applied another cooler on the cards, the temperatures went down instantly which made me investigate.

I'll make a long story short, when heat builds up in the GPU the fan RPM should throttle up depending the temperature (fan speed throttling), this does not work on the reference coolers at all. Now either AMD disabled the feature to preserve noise levels, or this is a bug in the BIOS. We can force the throttling manually with our own Rivatuner, forcing it at 60% (still very silent) will keep the temp below 65 degrees C.

In the current config/BIOS Fan Throttling does not seem to work and your fan will rotate at 30% only no matter how hot that GPU is.

	TUL Radeon HD 3850 512MB

Tul (PowerColor) sent us a version with a Zalman cooler on it. While that's beautiful to the eyes we have to mention that it runs on 100% power/RPM. It makes a lot of noise. It does proof though that custom cooling can get temperatures down a lot. We measured a plafond of 54 degrees C. An intersting tail to tell though, the lower temperature did not allow for a higher overclock.

These thermals at a maximum of 55 degrees are much better though.

	HIS Radeon HD 3870 512MB

Again, for the 3870 model HIS will release an ICEQ based version soon, that should give hope for better temperatures. We again see the the acceptable thermal delta as set by AMD is roughly 90 degrees C. Very warm, but not an issue for the product. Againw e believe his is a BIOS issue as fan throttling does not seem to enable itself.

What's good to mention is that this 3870 has the dual-slot cooler, it pushes the heat outwards outside the PC, preventing the ambient temperature in your chassis from heating up.

Thanks to manufacturers like HIS and TUL we'll see better cooled products.

Noise Levels coming from the graphics card

When graphics cards produce a lot of heat,  that heat usually needs to be transported away from the hot core as fast as possible. Often you'll see massive active fan solutions that can indeed get rid of the heat, yet all the fans these days make the PC a noisy son of a gun. I'm doing a little try-out today with noise monitoring, so basically the test we do is extremely subjective. We bought a certified dBA meter and will start measuring how many dBA originate from the PC. Why is this subjective, you ask? Well, there is always noise in the background, from the streets, from the HD, PSU fan etc etc, so this is by a mile or two not a precise measurement. You could only achieve objective measurement in a sound test chamber.

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement. Frequencies below 1kHz and above 6kHz are attenuated, where as frequencies between 1kHz and 6kHz are amplified by the A weighting. 

We start up a benchmark and leave it running for a while. The fan rotational speed remains constant. We take the dBA meter, move away 75 CM and then aim the device at the active fan on the graphics card.

• TUL 3850 - 49 DBa
• AMD 3870 - 41 DBa
• HIS 3870 - 40 DBa
• HIS 3850 - 39 DBa

All products, except the TUL card where within normal levels. At PC boot you'll get a quick scare though as the fans on the reference coolers quickly spin to 100% creating a lot of noise. Yet that's only for a couple of seconds. Not even under full GPU load the fans get noisy.

The TUL card as explained earlier already simply is spinning at 100% RPM constantly, and while that is getting us a great thermal cooling, it's quite annoying to listen to. Even in desktop idle the fan is loud. TUL however send out a version that is not 100% finalized.

Well, what do you guys and gals think, it's time to run some games on these puppies right ?