Page 6 - power Consumption and Temperature

Le pouvoir "The Power"

We'll now show you some tests we have done on overall power consumption of the PC. Looking at it from a performance versus wattage point of view, the power consumption is really not bad. 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:

The methodology is simple: we look at the peak wattage during a 3DMark05 session with hefty IQ settings 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.

We had a total system wattage peak at roughly 400 Watts with a single HD 2900 XT card, which is really a lot. We simply place a wattage meter in-between the PSU and power socket. It's not the most objective way to test as you have to consider PSU efficiency as well, but it's the best thing we can do though.

For Crossfire we only measured ~125 Watts more power consumption topping the system off at 526 Watt. Now that might sound strange, but the CF test was done with the help of an Intel D975BXB mainboard, and it consumes less power.

In my opinion, a single Radeon HD 2900 XT requires you to have a 500 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 35 AMP's on the 12 volts rails for stable power distribution.

I say this because the card itself will use a lot of AMPs on that 12-volts line. If we take the reference peak 215 Watt: 12 Volts that would be 18 AMPs for just one HD 2900 XT. And then you have the rest of your system to feed.

Notice that the card uses one 6-pin power connector and one 8-pin, I'd strongly advise a PSU with dual 12-volts rails here. You can also connect 2x 6-pin connectors yet overdrive (overclocking) will be disabled. If you want to do it exactly right; check out this PSU review please.

Why does the Radeon HD 2900 XT have two 6/8-pin power connectors? Well, the PCI Express spec allows for 75W from the edge connector plus 75W from each external 6-pin power connector. Then 75 Watts from the PCI-Express bus. The trick here is that the 8-pin connector can draw 150 Watts.

So mainboard 75 Watts, 6-pin connector 75 Watts, 8-pin connector 150 Watts. That's a total of 300 Watts at your disposal for a card that (non-overclocked) peaks at 215 Watts.

Crossfire, then you really should end up with a 800 Watt or better PSU with a 45 AMPs 12 Volts rail. Again, definitely check out this PSU review, please.

Dual Radeon HD 2900 XT in Crossfire requires some serious power management.

There are many good PSU's out there, please have a look at our many PSU reviews as we have loads of recommended PSUs 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

Les températures de la carte graphique

As with any graphics card we test, we also take a look at heat build-up in the GPU. This is a fairly complicated process to track properly and the one tool to do it with is Rivatuner. Let's have a look. They're all overclocked and the temps are varying very little. We measured at a room temperature of 22 Degrees C.

I inserted a good number of NV products here as well. We only recently started tracking GPU temps in this manner.

Much like NV's flagship product, the 8800 Ultra, the R600 (Jetway Radeon HD 2900 XT) also shows a new level of hotness. The cooler alone already revealed that it needs to dissipate a lot of heat. In fact the cooler alone uses 25 Watts to operate at 100% Temperatures are 100% the same as the reference model; in fact ... This card is a reference model. There is absolutely no difference compared to the card we tested in our initial reference review.

So, the Jetway Radeon HD 2900 XT is running really hot. The card was doing temperatures off the chart as it reaches 90 degrees C. Now much like the Ultra, the weird thing is that the product can deal really well with it. Despite that load temperature it even overclocked much higher, as we'll show you later on. It's however a lot of heat dissipation in your system though.

The beauty of the cooler design is that this heat is pushed outwards of your PC as exhaust at the connector side.