Intel Core 2 CULV Roundup: Who Needs Atom?

Blending Battery Life with Performance

We just showed how CULV skunks Atom when it comes to performance. Dual-core Atom 330 is still quite a bit slower, and it's not even close when we look at the mobile Atom CPUs. This is all from a relatively "weak" 1.3GHz Core 2 processor. But Atom CPUs have a TDP of just 2.5W for N280 and 5.5W for N450 (the latter also includes the chipset, so it actually uses less power than N280 + 945GSE); meanwhile, CULV is listed as having a TDP of 10W. Advantage: Atom, right? Well, not so fast. The newer Pine Trail platform definitely helps, with a much lower power draw from the chipset and graphics. Max TDP doesn't necessarily correlate well to idle or low use TDP, though, which is where most users tend to operate their PCs. Here's how battery life stacks up.

We gained performance but we do give up a bit in battery life - at least when we look at Pine Trail. The smaller CULV laptops like the Acer AS1810T are able to come very close to Atom N280 battery life in the Idle and Internet tests, while the video playback results still favor N280 (provided you're not trying to do 1080p H.264). Atom N450 on the other hand manages to boost battery life by anywhere from 10% (DivX) to 40% (Idle), putting it out of reach of CULV when both are using similar capacity batteries.

The AS1810T delivers an impressive result in our Heavy Internet Browsing test, coming in just shy of eight hours at 463 minutes. That's a virtual tie with the older Atom N280 based ASUS 1005HA (467 minutes), indicating CULV is able to render the web pages and get to a deep sleep state faster than N280. The newer ASUS 1005PE Pine Trail netbook still bests the AS1810T by just over two hours (590 minutes), so if you want maximum battery life Atom continues to beat the other Intel processors. The other CULV options both trail the AS1810T, which is expected. The EC5409u is larger and so the LCD will draw more power, while the Dell 11z has a slightly lower capacity battery.

In terms of relative battery life (and of course, we should note that we're going off the advertised battery capacities, which may be slightly off), the CULV and most N280 offerings are clustered tightly together. While the EC5409u does use more power, the DDR3 memory appears to mitigate that somewhat, with overall battery life still very close to the smaller laptops. Pine Trail is at its best in Idle battery life, but the Internet test is another strong point: it gets 25% more battery life compared to CULV for the same battery capacity.

Looking at power requirements helps clear up any lingering questions. Mobile Atom CPUs are designed to sip power, with their highest load sucking down around 4W for N450 and 7W for N280 (including chipset power draw). We estimate that at idle, Atom N280 uses 1W, the chipset probably uses 2W, LCD gets 3W, and the remainder is divvied up among the other bits and pieces. Atom N450 can cut another 1W from Idle power requirements, which is at least a 15% reduction (and possibly more, given our tools are only accurate to at best .5W). In contrast, a CULV CPU can idle very well, but under load the power draw jumps significantly. The AS1810T looks like it uses every bit of its 10W max TDP. Add on graphics and the gap widens even more, though here we need to mention that GMA 950/3150 are a very big step down from GMA 4500MHD (which is another big step back from something like GeForce 9400M).

Overall, it appears that CULV processors are very similar in terms of idle power requirements when compared to Atom N280, especially once we factor in chipsets. As we mentioned above, in many situations an application will need to do a set amount of work as quickly as possible (e.g. rendering a web page), after which the CPU can go into a deep sleep state. The faster the work gets done, the sooner the CPU can sleep, and the net result is that even in moderate loads CULV can compete quite well against N280. The catch is that there are other loads (like video decoding) where CULV ends up using quite a bit more power than Atom, but in common usage scenarios the battery life is still very good.