Does ram affect game performance ...can slow ram cause games texture to load slow and cause lag

Err .. Nopes!

Its the hard disk which is responsible for faster loading of textures and its the video card responsible for rendering them.
RAM just stores and recycles the already loaded textures so they don't need to be reloaded from hard disk. Yes it slightly affects the textures in highly demanding games but major impact is usually seen in applications.

Games don't tend to make use of faster RAM much. They require sufficient RAM instead (Size not speed in other words).

I'm no expert in this but I think you would do better if you get an hdd drive with 7200 rpm, it'll help you load a bit faster which will help with the lag. N if u have a bit of extra cash you can even get an ssd, say like a 120-240 gb drive, and add all your high demanding games onto it. Like I personally added crysis 3, lol, skyrim to mine, the games I play often. N ssd drive for 120 gb, goes for around 100 bucks.

I'm no expert in this but I think you would do better if you get an hdd drive with 7200 rpm, it'll help you load a bit faster which will help with the lag. N if u have a bit of extra cash you can even get an ssd, say like a 120-240 gb drive, and add all your high demanding games onto it. Like I personally added crysis 3, lol, skyrim to mine, the games I play often. N ssd drive for 120 gb, goes for around 100 bucks.

Your throughput when using an external HDD:
1) Most likely the WD HDD in the enclose is only a 5400 RPM drive. Most specs say if drive is 7200 RPMs (good selling point). They omit for 5400 so that you don't know.
2) If Using USB 3 it will be considerably faster, Still slower than internal HDD throughput, than using USB2.

PS when a SSD is used (For OS + Programs) with a "storage HDD). If you make a small partition on the HDD say 200->400 Gigs (=>for a 1 TB HDD). Put Most used files here.
IF HDD is for both OS, Programs and storage. This is still a good Idea, just set partition to say 500 gigs.
Reason:
This first partition uses the Outer edges of the Platters + Faster performance for what is stored at out edges compared to what is stored closer to the center.

Well what is your budget first of all. Since ssd's are expensive you might be better off getting the 1tb hdd drives that run at 7200 rpm. Since its much more hard drive space for your money.

If SSD is out of price range plus only about 120 gigs. Larger SSDs but even a 256 gig HDD is still around 200 bucks.

An alternative would be the Seagate 750 gig SHD. Has a small 8 gig internal SSD that allows for fast boot time + the 7200 RPM HDDs provides storage space.
IE: http://www.newegg.com/Product/Product.aspx?Item=N82E16822148837
NOTE is says a newer UPGRADED model is available - BS, yes it has upgraded the HDD to a 1TB but DOWNGRADED speed to 5400 RPS.

For Gaming there is VERY little diff between DDR3-1600 and DDR3-1866.
Also 8 Gigs is currently the sweetspot for Ram.

?????? Confused.
Should be using 2 identical modules for Dual channel operation.

Down load CPU-z.
Run it and click on the Memory tab - this will tell you Total size, what speed you are running at, and if single channel or dual channel. Also shows timings.

http://www.cpuid.com/softwares/cpu-z.html

Yes, most certainly, test results do show that gaming is affected by faster / lower CAS RAM. The question has always been whether the increase in cost is worth the increase performance. This is oft skewed by an improper basis as the analysis should not be whether say is a 5% performance increase in performance worth a 30% increase in RAM costs .... it's whether a 5% performance increase in performance worth a 3% increase in Total System Cost. Every situation has to be examined individually and the following test at anandtech was designed to present one set of conditions where RAM speed has a great impact on gaming performance.

http://www.anandtech.com/show/6372/memory-performance-16gb-ddr31333-to-ddr32400-on-ivy-bridge-igp-with-gskill/14

Assuming a $2,000 build ....

Metro 2033
DDR3-1600 is 3% faster than DDR3-1333 for a 0.2% increase in system cost
DDR3-1866 is 7% faster than DDR3-1333 for a 1.0% increase in system cost
DDR3-2133 is 9% faster than DDR3-1333 for a 2.8% increase in system cost
DDR3-2400 is 9.5% faster than DDR3-1333 for a 3.5% increase in system cost

Dirt3
DDR3-1600 is 9.5% faster than DDR3-1333 for a 0.2% increase in system cost
DDR3-1866 is 13.5% faster than DDR3-1333 for a 1.0% increase in system cost
DDR3-2133 is 15% faster than DDR3-1333 for a 2.8% increase in system cost
DDR3-2400 is 14.5% faster than DDR3-1333 for a 3.5% increase in system cost

In previous testing on the motherboard side, we have seen that Dirt3 seems to love every form of speed increase possible – CPU speed, GPU speed, and as we can see here, memory speed. Almost every upgrade to the system will give a better frame rate. Moving from 1333 to 1600 gives us almost a 10% FPS increase, whereas 1333 to 1866 gives just under 15%. We peak at 15% with the 2133 kit, but this reinforces the idea that choosing a 1600 C9 kit over a 1333 C9 kit is a no brainer for the price difference. Choosing that 1866 C9 kit looks like a good idea, but the 2133 C9 kit is reaching the law of diminishing returns.

Click to expand...

Batman AA3
DDR3-1600 is 8% faster than DDR3-1333 for a 0.2% increase in system cost
DDR3-1866 is 15% faster than DDR3-1333 for a 1.0% increase in system cost
DDR3-2133 is 21% faster than DDR3-1333 for a 2.8% increase in system cost
DDR3-2400 is 22% faster than DDR3-1333 for a 3.5% increase in system cost

Bit-Tech's test are probably more applicable to what most here would experience, though we are hampered by a 489 GFX card

http://www.bit-tech.net/hardware/memory/2011/01/11/the-best-memory-for-sandy-bridge/6

In Civ 5 on one hand one might say that a 2 fps increase is not noticeable, however that's a 9.5% increase in the min fps ..... for a 2.8% increase in system cost. 9.5% is oft the difference in cost between one GFX card and the next GFX card in a higher cost bracket.

Also note that 2 x 8GB will usually do better than 4 x 4GB as the memory controller has to work harder handling the extra 2 modules.

As to the Hard Drive question, given the indicated level of technical expertise, I'd strongly suggest a hybrid SSD / HD. These are boot times on otherwise identical hardware (Rampage Extreme, 2600k @ 4.8 GHz, 2 x 4GB, twin 560 Tis @ 1000MHz).

Seagate Barracude XT - 21.2 Seconds
Mushkin Chronise Deluxe (THG 1st Tier SSD) - 15.6 seconds
Seagate Momentus XT Hybrid - 16.6 seconds

http://www.newegg.com/Product/Product.aspx?Item=N82E16822148837