Okay I am sure you are all familiar with both these specs but here goes anyway.
I am going for i5 because well...I have a gaming desktop and why would I need it if it get so hot and doesn't last at all. Unless it's a HUGE performance boost I don't see a point. If anything, I'll install an SSD and more RAM.
Lenovo is 14" and 2.63 kg vs HP is 15" and 2.63 kg. If that matters to you.
Ruggedness and reliability over time. Lenovo might have a slight edge over HP but you could get a 'Lenovo lemon'. Overall, if you take good care of your notebook I think chances are it works out about the same.
Found a long Lenovo Y470P forum thread with posts from actual owners.
They posted a GPU-z screen shot that confirm DDR3 version.
It's probably worth looking over: Lenovo Y470P topic
One item mentioned. The markings on the notebook are just Y470. It's not marked as Y470P. That's normal and it's the HD 6790 that makes it a P model.
A word of caution as an owner of a Lenovo IdeaPad Y470. The CPU gets hot when playing games. I've read through some of the comments in the link WR2 provided and there were a few comments of the CPU reaching 90C on the Y470p laptop. The only difference between the Y470 and Y470p is the Radeon HD 7690m.
Based on my review, the CPU temp does in fact reach 90C - 92C. While testing GTA 4 the CPU hit 99C and it started to throttle down. It was easy to tell 'cause the game started to stutter. I purchased a laptop cooler (Cooler master U2 with 2 moveable fans), but it had no effect on the temperature.
I've read a few professional reviews of the Y470 after I purchased mine and those reviews also confirmed the 90C+ temps. But the reviewer were unconcerned about the temps because the laptop remained stable and the CPU did not throttle. Then again, they did not test GTA 4 on the laptops.
Laptops have two main enemies; an incompetent owner and heat.
However, HP's quality control took a dive in recent years which led to a few class action lawsuits against them for certain laptops. Have they made any design improvements for more current laptops? That remains to be seen.
The Lenovo Y470 / Y480 / Z470 / Z480 all seem to use the same chassis based on some research. The only thing different are the components. The Y series is Lenovo's "gaming laptop" while the Z series is "mainstream". The difference is the Z series uses less powerful discrete graphics than what's available for the Y series.
It seems that the reason why everyone who measures the CPU temp in the Y470 is getting 90C+ is because of the thermal paste. Karneey, in the link below decided to replace the thermal paste with Phobya HeGrease Extreme and his CPU temps immediately dropped by 20C+. While he did not go into any real details, it seems Lenovo did not do a very good job about placing the thermal paste.
There is one caveat to replacing the thermal paste... it voids your warranty. Generally speaking, not a big deal, but I added the option for a 2 year warranty extension for my Y470; I think it add an extra $30 - $50 to the total cost. I originally planned to replace the thermal before I bought the Y470, but that wasn't going to be until after the warranty expired (3 years in total).
The new z that is coming out is going to be more powerful than the y470, and since it's a multimedia laptop, the price is going to be fine for something brand new.
This laptop doesn't need to run anyway super well or anything. It's going to be gamed on maybe for 2 hours if anything sometimes with lowered setting.
I have my desktop for gaming and this laptop is basically going to my sister for her to play WoW on or whatever when I need my desktop.
As long as you are aware that of the potentially hot running CPU... I don't know how much WoW stresses the CPU, but if it is similar to Crysis, Fallout 3 or Mass Effect then It'll likely hit 90C. If it's as stressful as GTA 4, then it'll be 99C; I really doubt it will be that stressful. If it WoW only stresses the CPU like King's Bounty: Armored Princess, then the CPU will likely be around 82C.