Intel Core i7 Presentation
"OC3D were present at Intels recent Core i7 presentation at Heathrow. We'll take a look at some of the new features and what they do"
Turbo Mode is a feature that has been spoken about quite a lot recently, but there have been many mixed claims about just how it works in Nehalem. Whilst it made its debut with mobile Penryn, it never really got a chance to actually work. What it was designed to do was if for instance you had a dual-core mobile Penryn CPU running a single threaded application, leaving one core totally idle, and the chips TDP was lower than what it was designed for, then Turbo Mode would aim to increase the clock speed of the active core. The reason this didn't really work was due to a lot of applications (starting with Vista) bumping the single thread load around active cores leaving them unable to initialise Turbo Mode for any length of time.
In Nehalem, this feature has been refined to work a whole lot better, largely in part to the CPU. The idea is pretty straight forward in that if you have a quad-core CPU and only two of the cores are active, then as long as the CPU detects that the heat levels are ok and the power levels are under the TDP, the two idle cores can be shut down and the two remaining active cores will be overclocked.
Turbo Mode can also come in to effect even if all four cores are active, so long as the CPU detects heat and power levels are under their set limits. In this case all four cores would be given a boost as per the slide below (bottom right). All Nehalem processors will at least be able to go up a single clock step (133MHz) in Turbo mode, even if all cores are active. Just as long as the CPU detects that the TDP hasn’t been exceeded.
At present the level of overclock isn't very significant, and for now will more than likely be around 266MHz. Intel does however have large ambitions for Turbo Mode and we should expect to see higher boosts in the future.
Intel also claim that the CPU is aware of the conditions it's running in, for instance if your case is very cool or you have water-cooling, then the CPU will recognise that it is well under its TDP and push the clocks potentially quite a bit higher. It remains to be seen whether this will be the case on the first Nehalem CPU's released and from what I can gather it wont be.
While this feature might not excite most of us that much, for the not so avid overclocker, it could provide a very welcome extra performance boost with absolutely no effort.
For the rest of us, Intel confirmed that Turbo Mode can just be turned off in the BIOS which made me happy.
While Penryn was well received (especially the dual-cores), it didn't really give any major leaps in performance, but with AMD's Barcelona / Phenom CPU not really challenging Intel, it was a welcome release regardless. But even then, a lot of people were just looking forward to Nehalem and hoping it was going to provide the next giant leap forward in CPU performance. Now we are getting very close to the release of Nehalem and the anticipation is building.
I find myself one of the lucky ones to have witnessed first hand what Nehalem can do, and I must say I was very impressed. But with precise performance numbers still under NDA, I can't pass on any of the detailed information that I saw.
That said, I'm still going to give you a rough idea. Gaming at present seemed to offer gains of anything from 8% to 40%. This is very vague I know, but it's the best I can do. The place where Nehalem really excelled, however, was in encoding and rendering. I saw an Nehalem CPU ray tracing on-the-fly and doing an amazingly good job of it. Encoding in programs such as Adobe Premier Pro and Sony Vegas 8 saw gains anywhere up to 60% on a comparable Core 2 CPU.
So you’ll need a new motherboard and CPU (obviously), and perhaps some new memory, but if you’re running well threaded applications then Nehalem will knock your socks off.
I'm just looking forward to Nehalem's release, so one of our reviewers can get their mitts on a sample to put through its paces and share with you what it can do.
Let us know whether you will be one of the early adopters of Nehalem in our forum.
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