Win7 vs. Win8 on Haswell

I'm building a desktop using a Haswell CPU and a AMD Hawaii Architecture GPU. I'm looking into buying and OS to use but have ran into a bit of a dilemma. I really like Windows 7 and haven't been very impressed from what I've seen on Windows 8, but would there be any negative side effect to running Windows 7 on this set-up as opposed to Windows 8? I know Haswell supports a bunch of new power control features built into the architecture. Will these new features be supported on 7, or will I have to go to Windows 8 to make full use of the hardware? Is there any other reason I should avoid using 7? Could DirectX support be an issue? I'll force myself to bear with using Windows 8 if it'll help me get the most out of this new hardware. Thanks.

Nothing yet, but some time down the road with a new graphics card there could be a matter of getting something extra out of DirectX in a game. Intel will fully support the Windows 7 architechture for a very long time since it's what most of their corporate users are and will be running.

Thanks for the response. So all of Haswell's low power modes and hybrid memory caching support work fine in Windows 7? That would be great if so, as I could happily stay on Windows 7. Future Direct X support isn't that huge of a deal for me as I can always upgrade to a newer version at a later date if it become an issue. Who knows, maybe Microsoft will come to their senses and revert (or at least give the option to revert) some of the bad decisions made in Windows 8 in a later version by then.

Windows 8 does boot up faster and has performance tweaks here and there, like the task manager. You can mount ISO's by right clicking them and windows explorer IMO has better tools and options for navigating and adjusting files/folders. The only real problem I have with it is the start menu, which is really the only issue I have with it. Other than that it is a stable, reliable OS as much as 7 is. All my old programs from windows 7 work just fine compatibility wise. I was skeptical also after using 7 for years but after some tweaks I actually like it better. Get StartIsBack for a start menu and you won't notice the difference. I never see the forbidden start screen when I use my system. It's like I'm using Windows 7.5

I have power saving enabled in windows 7 through Asus AISUITE and in BIOS. It works fine.

Yeah they support everything for Windows 7, and their SSD caching routine is older than Windows 8 anyway.

For laptops/tablets they have a tech with Haswell that allows for low power activity like fetching email while the system is essentially in sleep mode, but that only works for 32bit Windows 8 so far, so it's quite esoteric.

There is what seems to be a fairly well founded rumor that Microsoft are at least seriously investigating the possibility of truly bringing back the start menu as an option for a Windows 8.2 or 9.0. Not likely to see the light of day until 2015 if ever, but you should easily be able to avoid Windows 8 until then. ;-)

Thanks for the responses! From what I've heard  here I htink I'll just use Window 7 for now and see if Microsoft can do better in the future.

I feel bad that Windows 8 doesn't get the credit it deserves.  Yes the stupid stuff is out in the open, but Windows 8 has so much optimization done over power management.  I can overclock a bit higher with Windows 8 with less power than on Windows 7.  That's quite a big thing for us overclockers that gets way overlooked.