If you thought that tracking processors, clockrates and TDP figures was hard last year, just wait until later this year when ‘programmable TDP’ CPUs hit Ultrabooks. It looks like we’ll have to make a change to our product database to accommodate this new idea in multi-use CPUs.
[TDP is the maximum power a CPU/GPU will use at full load and is an indicator of thermal dissipation and important when designing small, think devices that can’t have big fans or big heatsinks.]
Up until now, Intel CPUs have been labelled based on their nominal clockrate figures. With ‘Speed Stepping’ the CPU clocks were allowed to range between a min and max figure. With the introduction of Turbo, the idea of short-term overclocking was introduced. Although it became hard to determine long-term performance figures due to thermal capping, there was always a relationship between the CPU part number and the clock min and max range. With programmable TDP CPUs, that’s not true any more because one part number can now be configured by the manufacturer to perform at different programmable ranges and nominal clockrates based on the thermal requirements of the design.
VRZone have published some details of the new mobile CPUs which include the new programmable TDP features. Details are also given on the two previous parts we’ve reported on, the Core i5-3427U and Core i7-3667U. All the parts are new ‘Ivy Bridge’ designs and should be in devices in the June-July timeframe.
All of these CPUs have potential to be used in Ultrabook designs.
The range starts with a Core i3 at 1.8Ghz. Remember that the TDP figure includes GPU.
- Core i3-3217U – 1,8Ghz with speed-stepping down to 800Mhz. No turbo. Nominal TDP 17W, programmable down to 14W. Graphics clock maximum – 1050Mhz (locked)
- Core i5-3317U – 1.7GHz (at 17W TDP) with speed-stepping down to 800Mhz and Turbo up to 2.6Ghz (or 2.4Ghz dual-core) Programmable TDP of 14W (unknown nominal clock) or 17W. Graphics clock maximum – 1050MHz (unlocked)
- Core i5-3427U – 1.8Ghz at 17W TDP, 2.3Ghz at 25WTDP with speed stepping down to 800Mhz.
- Core i7-3517U – 1.9GHz again with speed-stepping down to 800Mhz. Turbo goes up to 3.0Ghz (2.8Ghz dual-core). TDP ranges are 14, 17 and 25W.
- Core i7-3667U – 2Ghz at 17W TDP, 2.5GHz at a 25W TDP
VR-Zone suggests that the parts ending in ‘17’ will be the Ultrabook parts at they lack some high-end technologies not commonly needed in consumer laptops. I’ve highlighted those parts above.
What you really need to know is not the part number but how a CPU is programmed inside an Ultrabook. A higher programmed TDP will indicate a higher maximum sustained clockrate although in the Ultrabook world, all parts are likely to be programmed at 17W TDP with some lower-end devices (or smaller devices – 10” and tablet designs come to mind) using a 14W TDP setting. Overall though there’s some useful increases in sustained clockrates but a larger gap between Core i5 and Core i7 than we saw in previous Ultrabook CPUs.
Why ‘programmable TDP’?
When a silicon die can be produced at a high quality and high yield rate it’s simpler for Intel and for the manufacturers to be able to buy one part and to program it such that it can be used in different thermally limited designs. For most users it means nothing. For part number watchers, it means a little more work in determining nominal clockrate and for hackers, there’s potential to do some modding.
We’ll keep you posted on the details of Ultrabooks that launch with differing configurations and you’ll always be able to view the CPU name and the nominal clockrate of devices in our database. As always, be aware that short-term testing of CPUs at high Turbo rates to produce performance figures is not a good real-world test.
This article written on a current generation ‘mobile’ Core i3 2330M, nominal 2.2Ghz locked at 800Mhz – Yes, if you want lower TDP, you can always choose ‘power-saver’ mode in older generation CPUs!