How do you build gaming computer under 1000 that would run Skyrim and bf3

With $1,000 you should be able to build a gaming rig that will play all games available now and for the next 12 months (including Battlefield 3) with high resolution settings.
Graphics Card


Always start with your graphics card. If your graphics card is subpar, then it doesn't matter what the rest of your gear looks like as you'll still not be able to play your favorite games. If we take 25% of $1000 we should be shooting for a graphics card right around $250. In that price range we recommend you go with the GTX 560, which recently dropped in price to $225. There is also a newer model of the GTX 560 the "DS" which has dual fans that will cost you a few dollars more. The Radeon alternative in this price range is the HD6950. If you are willing to flash the bios and void your warranty, you can flash the bios on the HD6950 to turn it into effectively what is a HD6970 (a card that usually costs $70 more). If you want a less expensive Radeon card, then go with the HD 6870 which you can find for $199.


CPU


If we follow our rule of 25% for our CPU as well, then we would be in the same $250 range; however we recommend you make a step up to the $300 range and go for the i7-2600k based on the all new Sandy Bridge technology. For around $100 less you could also consider the i5-2500k which doesn't include the hyperthreading that the 2600k does; however, does boost to 3.6Ghz and has 4 core processing which is plenty good enough for any games coming out in the next several years.
If you are an AMD fan or would just like to save some money, then go with the AMD 1090T X6 Phenom II CPU and you'll actually be under your price budget. You could then consider using that left over money on a better GPU or motherboard.


Motherboard


It's probably in your best interest to go with a Z68 motherboard at this point in the year if you plan on using an Intel CPU. We like the Asus P8Z68-V PRO. For Z68 motherboards consider using a smaller SSD as cache to give it SSD-like performance with Intel's Smart Response Technology.
For your motherboard we recommend you go with the Asus P8P67 Deluxe for around $220 or the MSI P67A-GD65for around $180 (less if you can find a rebate). If you went with the AMD processor, then go with the Gigabyte G8-890GPA-UD3Hfor around $130 as it is AM3+ ready if in the future you decide to upgrade your CPU to the Bulldozer series.
What's left?
At this point you could have a pretty wide variety of prices. If you chose our most expensive options, then you'd be right around $800 already while with less expensive options you would be around $510. Going forward we'll assume you are in the middle of these two options at right around $650.
Ram


For your $1,000 gaming pc you should plan to have at least 8GB of DDR3 (240 pin) ram. It's your choice as to whether you go with 4GB sticks or 2GB sticks (generally 2GB are cheaper). For faster ram check the "timing" and speed of the ram; however, keep in mind that if your motherboard can't handle the speed of the more expensive ram, that it will default down to a lower speed. We suggest you get something like the Patriot 2 Gamer series or the G.Skill Rip Jaw Series. To stay within your budget, make sure it's under $100.


HDD
As far as a hard drive try to get one that is the newer technology, Sata III/ Sata 6Gb/s. We recommend this Seagate Barracuda 2TB drive (Sata 6Gb/s but only 5900 RPM) or if you'd rather make sure you get 7200 rpm this Western Digital 1TB Sata 6Gb/s 7200 rpm HDD.
DVD RW/ Blu-Ray Drive
For a DVD drive we'll go with the Lightscribe DVD RW - (around $25).
Blu-Ray. If you want an inexpensive Blu-ray drive you could go with the Lite-On for around $60 or if you'd rather have a trusted brand name, then go with this LG one for around $100.


Case


For your case we recommend you go with either the Cooler Master HAF ATX Case for around $100 or the Cooler Master Elite for around $39. If you want a full-size case go with the Haf 932 (around $154).
Power Supply/PSU
For your power supply we recommend you get one that's anywhere between 650-750 watts. This Corsair 650w PSUwould be our suggestion for around $85.


But these are all the important bits you can include other Hardware like Sound cards for HD sound but this hardware is just optional as these days sound is integrated onto the motherboard.


Sorry if i missed anything.
And also I'm from the UK so I don't know if the money is right as we do not use dollars here. But I checked on US websites to see if I was right. I did this to help you if you from the US.