Ivy Bridge Configurable TDP Detailed
by Anand Lal Shimpi on September 12, 2011 2:28 AM EST- Posted in
- CPUs
- Intel
- Ivy Bridge
At Computex Intel announced that Ivy Bridge would be its first processor to support a configurable TDP. Today all CPUs are rated at a single maximum TDP. Mainstream notebook processors fall in the 35 - 45W range, while mainstream desktops are around 65W. As the world embraces mobility and interfaces like Thunderbolt enable new usage models for notebook users (e.g. docking station with a beefy external GPU), Intel had to rethink its power strategy.
Today with a 35W CPU, Intel guarantees the OEM that if it implements a chassis and cooling system capable of dissipating that much heat the chip will operate as intended. If the OEM offers an optional dock or high-performance cooling mode that could cool a higher wattage chip, the CPU can't take advantage of it. Ivy Bridge changes this.
Ultra low volt (ULV) and extreme edition IVB parts will carry three TDP ratings: nominal, a lower configurable TDP (cTDP down) and an upper configurable TDP (cTDP up). Let's talk about cTDP up first.
ULV Ivy Bridge parts will be rated at 17W, similar to the ULV SNB CPUs that are used in Ultrabooks and the new MacBook Air. Intel will also guarantee these chips at a higher frequency with a TDP of 33W. If the Ivy Bridge MacBook Air could dissipate 17W of heat normally but when placed on a docking station with additional cooling capabilities could remove 33W of heat, the CPU would simply run at a much higher frequency when docked. This goes beyond simple turbo as it exceeds the CPU's nominal TDP, whereas turbo mode is mostly bound by TDP.
The same applies in reverse. If you want the chip to behave as if it were a 13W part instead of a 17W part, that will be possible as well. It's configurable performance based on the current conditions. If you have tons of cooling ability, you get more performance. If you need battery life, you get a chip that makes your system behave like an ultraportable.
The extreme edition IVB parts will also support configurable TDP. 55W parts will be able to go up to 65W or go down to 45W.
You can expect that Intel will use configurable TDP as a reason for customers to buy the more expensive versions of Ivy Bridge. Ivy Bridge is expected to arrive on notebooks and desktops in April - May 2012.
Facebook
Twitter
RSS
26 Comments
View All Comments
jjj - Monday, September 12, 2011 - link
april-may? slidong further 1 more month?tuklap - Monday, September 12, 2011 - link
they are really going to match the next gen APUs at the ivy bridge release...price cuts!!!yankeeDDL - Monday, September 12, 2011 - link
I think this is a neat feature, but I really don't see the big fuss about it.Basically, you take a 3GHz CPU with a TDP of 65W, underclock it and undervolt-it (if that's a word) and get a 35W configuration.
When mobile you use the latter, when docked you use the first.
What I find a bit tricky is how are you going to do, in practice, the extra cooling. Fans are not exactly power hogs, so keeping them at lower RPM, may spare you some noise, but power?
On the contrary: docking usually limits (slightly, but it does limit) the cooling solutions, as it partially wraps around the mobile device.
quiksilvr - Monday, September 12, 2011 - link
You're not factoring in the energy the CPU itself takes.yankeeDDL - Monday, September 12, 2011 - link
Either I don't understand your comment, or you're wrong.I am accounting for the energy that the CPU itself takes: that is the TDP ...
The system needs to have a cooling arrangement that enables it to dissipate the heat generated at the highest TDP. So this feature, does not bring advantages there.
Setting lower TDPs, makes you save energy, and therefore increase battery life. But that is already covered by SpeedStep and similar techniques. I guess this gives you another knob, but I cannot imagine in which practical application this makes any difference: today I cal already set the max frequency of the CPU (and possibly lower the voltage too).
The only example that this article brings is when a laptop is docked, the CPU speed can be cranked IF higher cooling is available. This is, I think, the only reasonable scenario where this makes sense. Now think about the cooling solution of a normal desktop CPU with 65W TDP, and imagine implementing something like that in a laptop. You can't.
Alexvrb - Tuesday, September 13, 2011 - link
I think quiksilvr was trying to say that a laptop might have the cooling capability, in that it can ramp up fans even more. But they wouldn't do that when it is mobile (undocked) because it's not necessary because the CPU is running at a lower frequency/TDP combo to save power.So when you dock it, no more battery power concerns, ramp up TDP, ramp up clocks, ramp up fans. You could even use larger diameter (possibly TMD) fans that run at very low speeds when mobile, so that when you dock they don't need to scream.
Alternatively the dock itself will utilize large fans and push air into the system similar to using forced induction on an engine. I don't think they'll get as elaborate as an intercooler, however. But they could if they darn well wanted to - they could even use a compressor and blow chilled air into the laptop intake(s). The dock itself could even be heat conductive, hollow and finned, and pull heat away from the entire laptop chassis.
It all depends how elaborate the OEMs want to get. I think in the end only very high end boutique vendors will really make good use of this. Maybe determined modders too.
yankeeDDL - Tuesday, September 13, 2011 - link
I think I understand your point: you say that the cooling solution does not need to change, in principle, but you cup the TDP when mobile to avoid draining your battery.With the current solution (SpeedStep), this is only up to the user, and in any case the CPU has no way to know whether it is docked or not, in order to enforce the TDP limitation.
I can see a small added value here. Although, if you think about it, all OSes today are aware of whether a laptop is docked or not, so it would be easy to implement a TDP capping in SW. I would think so at least.
In any case, thanks for your explanation.
mathew7 - Tuesday, September 13, 2011 - link
Maybe this will open the market to some docking stations with small AC units, so that not only will air be forced into the laptop (fans), it will be also cooler than ambient.There are plenty of ideas.
PS: I think it would be nice to have a 12"-13" laptop with good battery life which would still be usable as a gaming PC while docking with an external GPU (so the CPU could "upgrade" itself...of course this would require more than 10% TDP boost).
blueeyesm - Monday, September 12, 2011 - link
There'd be a few ways. One would be an intake fan over the exhaust port of a laptop, for example, that force draws air into an airway and exhausted out the dock itself. Or, say two small posts that the laptop docks onto could be used (although somewhat inefficiently).Use your imagination and dream up a solution :)
iwodo - Monday, September 12, 2011 - link
Sorry how is this different from SpeedStep? And Turbo Boost? Isn't it basically a "power usage" marketed version of the two above. Where as Speed Step and Turbo Boost were marketed as a performance oriented features?