Q6600 vs E8400 (Scrap Build for Brother-in-Law)

Building my 13 year old brother-in-law his first PC since his Xbox 360 has died, luckily I got most of the bits here to build one for him, got a 2GB GT 640, a Abit AW9D-Max 775 motherboard and a old ass Antec 900 and generic PSU that should do for the mean time, only thing I need is a decent sized hard drive which is easily sorted and a decent CPU, I can either get a E8400 for €8 or a Q6600 for €25 both from CeX with 2 year warenties.
Obviously the Q6600 is the obvious choice however here's the kicker, I will not be overclocking since it only have the crappy stock heatsink and since the motherboard is quite old I rather not push it any so it will last longer for him untill he can upgrade it himself, he'll only be doing gaming at 720p on a old monitor I'm giving him and will be playing games like GTA 5 and Fallout 4, so which is better for the task? the more effiecent and higher clocked E8400 or the quad-core Q6600?

Q6600, games like GTAV and Far Cry won't run very well on pure dual cores

The dont like overclocking in old age. tried overclocking my Q9550 in hopes to get rid of the slight cpu bottleneck with my gtx 560 in battlefield 3. I managed to get an extra 70MHz before it became unstable.

I've got a Q6600 + GTX 670 and it's still a very capable 1080p gaming machine now!

It does have 8GB of Ballistix DDR2 RAM and yes it does run at 3Ghz but that was just s basic bump in FSB from what I remember, it's been a while. Mine was a decent stepping CPU though so I guess that helped. If it supported VT-d then it would still be in daily use for VMs

It would be worth buying a 2nd hand socket 775 cooler just to get that little bit more GHz IMHO. There must be a few on Ebay etc. Until I looked recently I didn't realise I had 3 kicking around in my spares pile!

Q6600 there is a major difference between going from a dual core to a quad core cpu. Games will run better on the Q6600 regardless. Check out the Scrapyard Wars from LinusTechTips, although cringe worthy but learnt something from there.

Thanks guys, be going with the Q6600 for sure, he's already got 4GB of random RAM going with it (x2 1GB stick and x1 2GB stick) leaving one slot free, might add another 2GB stick if there's money left over after acquiring a hard drive which frankly I'd prefer if he picked up new.
Good thing I'm going with a Q6600 too as there's no gambling here on what stepping chip I'll get as the board supports all Q6600s but with the E8400 it only supports the C0 stepping and not the E0 chips, and it would of been a huge gamble as CeX don't tell you what stepping your getting:
http://abit.ws/cpu-support-list/mb/intel_975x_aw9d_series.htm

Go for the Q6600. I own one of that and is still a decent CPU for gaming but not for MMOs games. Someone in the forum was selling a really good Asus Server board compatible with the Q6600. You may jump on that, throw in a Hyper 212 and give it a little boost with overclocking.

The cooling isn't the only concern with overclocking it's also the fact that the board is really old and may not cope and I'd rather have it last him as well since it could be a few years till he can upgrade himself since he's only 13

Yeah, I wasn't talking about overclocking on the board you're talking about in the main post but overclocking on the good Asus server board a user was selling here in the forum. If you're concerned about overclocking anyway might still be a good idea get a better board anyway, if it's in the budget. I didn't want to suggest even more to overclock on the board you found because you already addressed that in another answer :)

new board would be out of the question, 775 boards are quite rare where I am and can go for a pretty penny because of it, also he'll be buying the components required himself with his savings, only got about €50 to work with which should get him the hard drive and the processor is being paid with the games he's trading in

Oh well, I wasn't aware of that. I'm sure he will still be super happy of the new PC he's getting!

Exactly, especially considering Fallout 4 wasn't released on the 360 and he has been dying to play it, more than what I got when I was his age

Tech always getting more powerful and a lot cheaper. My first PC was a used Toshiba Satellite notebook with an external floppy reader, no audio port and an expansion card to connect it to a 56k modem that's it. I had a ton of fun even with that thing :,)