Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus

Power Consumption

The reduced platform power consumption of the Core i5 and Core i7 CPUs is immediately apparent, even at idle. Both Lynnfield-based designs dip in around 20W underneath the Core 2 Quad Q9550S, which we’ve been using up until this point to replicate the performance of a standard Q9550. The ‘S’ model has a 65W TDP though, so the fact that Core i7-870 and Core i5-750 suck up less juice at idle is impressive. So too is the idle consumption of AMD’s Phenom II X4 965 BE, which also ducks in under the Core 2 Quad.

Fire up the Small FFT test in Prime95, add a FurMark Burn-In test, and the power usage jumps through the roof. Here’s where Intel’s low-power Q9550S shines, turning in the best results. But the two Lynnfields continue to impress with the second and third lowest power consumption figures. AMD’s Phenom II X4 965 comes in fourth, followed by the Core 2 Extreme, and trailed by the 130W Bloomfield-based Core i7-920.

It can be difficult to take thermal design power specs and give them real-world meaning. However, when you do the math, these load numbers make good sense. The TDP of Intel’s low-power Core 2 Quad is 30W below Lynnfield’s spec. Subtract out a power-hungry northbridge and you’re looking at the gap we see here in practice. Add 22W to the X58’s power budget and then take Bloomfield’s 130W ceiling into account; it’s no wonder Core i7-920 sits at the other end of the spectrum.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • caamsa
    Dang! AMD better get their $4iT together. Now I need to decided between i7, i5 or phenom II when I do my next happens too fast. Looking forward to more reviews on the i5 and mb prices.
  • People need to be careful when comparing the i7-870 to a i7-920, alot of people pre-release were worried that the 1156 platform was going to dominate the 1366. However when you see the 870 out perform the 920 people need to remember that a 870 is double the price of a 920, and even when you factor in a motherboard a 920 setup comes out cheaper than a 870.

    Now the i5 750 on the other hand is great performance at a great price, and would certainly be the budget gamers new weapon of choice.

    I currently have an i7-920 setup which is my main rig and am very happy with it and not at all upset to the see the 870 outperform it (since the 870 would cost me twice as much). I also have had an i5 750 setup now for over a week (the 1156 processors and motherboards have been available here in Australia for nearly 2 weeks now) and it is an amazing processor for the price of it.

    So what am I trying to say? 1366 is still a good platform for the top end of the market. The i5 are fantastic new processors for their price, and the 1156 i7's are just confusing and I'm not really sure who they are going to appeal to? I could understand it if Intel launched the 1156 i7's in 6months time when alot of users are already using the 1156 platform and are looking to upgrade their CPU without a new mobo. But to anyone looking at getting a 870, just get an 920 and use the extra cash on the mobo and ram to go with it.
  • Nintendork
    A little confusing the charts.

    I would prefer a bench with HD4890. They scale better in CF.
  • aspireonelover
    I can tell, I'm gonna fall in love with the i5 processor
  • cabose369
    Intel needs to come up with a simplified naming system for their products. They are as bad as NVIDIA is right now in terms of naming their products.

    There is sooo much to learn and there is so much information here.... I feel confused!!
  • alikum
    Well, I just hope that the Core 2 Quads will drop in prices significantly so that I could grab the high-end one for my final LGA775 upgrade!
  • buzznut
    Well this is good news for consumers. I'm not certain why it took so long for Intel to make some mainstream proc like i5, but for intel fans it seems worth the wait.
    This will also compel AMD to bring some more value to the market. Nice article.
  • jawshoeaw
    damn, 150 watts at idle?? Is that just the cpu? I hope the gaming rigs built on these processors are not left on 24/7. My old AMD X2 3800 system including the monitor uses less than 150 watts at idle (50 of which is the 22" LCD).
  • unclewebb
    i7 Turbo is a good tool to monitor the multiplier of Core i5/i7 CPUs.

    It uses the method that Intel recommends in their November 2008 Turbo White Paper.
  • evolve60
    "Intel Core i7-920 Extreme (Bloomfield) 2.66 GHz, LGA 1366, 4.8 GT/s QPI, 8 MB L3, Power-savings enabled"

    Since when has the I7-920 become an extreme?