Importance of CAS Latency in an APU?

I'm building my friend a budget gaming build(trying to get him into PC) for around 350 euros and while I was checking parts for him, I ran into an inquiry with the RAM I was choosing. I know in some of your's/Logan, (depending on who reads this) videos from the INBOX.EXE a while back that you discussed what CAS Latency was and how it affected gaming and general purpose use in computers. I was curious to know how it would affect an APU though, do to how much the graphics rely on it. As of right now I have the choice between 4GBx2 modules of 2133 MHZ at CL of 11 vs 4GBx2 modules of 1866 MHZ at CL 9 for about the same price(60 euros). Is there anything else important I should consider when choosing parts for APU builds?

1866MHZ memory:

2133MHZ memory:

Thanks for the help! Sorry the links are in French, I live in France.

The rest of the system:

CPU-AMD A10-6800k

MB-MSI FM2-A75MA-E35 Micro ATX FM2

HDD-1TB Caviar Blue

PSU-Corsair 430W Bronze 80+

Case-Xigamatek Asgard II

CAS Latency is not as important as memory speed for APUs. Since you are building a Richland APU system for him, get him 2400 MHz 2x4GB RAM and a H60 or H80 cooler to overclock the CPU and GPU simultaniously. I would seriously recommend you get an FM2 motherboard with a A85x chipset with a decent power phase like this ASRockĀ

It will perform overall better than using that older cheap crap motherboard with a A75 chipset and some crappy 4+1 power phase.

Multiplier overclock only on the cpu if you can.

..Unless you are aiming for a really high overclock on the fsb that is, then the lower value on the memory divider will be nearer to the rated memory speed.

Do you get what I mean or am I garbling it?

Multi-threaded performance suffers with a higher CPU multiplier but you gain better single threaded performance. Transversely overclocking the NB bus speed to 300 with 2.65v and dropping the multiplier and RAM/CPU/NB dividers gets you better multi-threaded performance. The multi-threaded performance is getting more and more relevant especially with modern Win 7 and 8 programs making use of more than just 2 cores at once. I saw a drastic increase in how fast my startup programs load just by overclocking the NB instead of the multiplier recently.

Wow, that's a lot to take in. Haha, but I will definitly look into all of it. The thing with his build is that his max budget is 350 euros(at least for the moment) so I don't know if I could fit 2400 MHZ RAM into the buidget, but we will see. As for the watercooling I will mention it to him for a future upgrade because it is a good idea, but because he is a "novice" in the world of computers, he may not want or understand something that "high maintenance". Though in the case for the A85x chipset motherboard I will definitly be getting that in there. Do you recommend any other brands besides ASRock as they are a brand I do not like as I have had bad experiences with thier motherboards in the past. Another thing with pricing between France and in the US is that it is usaully cheaper there in pricing than it is here. But thank you very much.

That specific board is not a skimpy bargin bin one so I would recommend that one or the one from Asus that is also m-ATX with 8-pin CPU connector. The one from Asus is a little bit more expensive though, basically you are paying for the branding with that one, the motherboard is pretty close to the ASRock one I linked.

If you can talk him into raising the budget by 150 Dollars, you can get him a decent system with the ability to be overclocked with room for expansion.

I'll try to see what I can do with him raising the budget up a but, so far I got him to do 400 so I could include the motherboard you recommended and at least a hyper 212 evo with the rest if he can't raise it any higher. Thank you very much for the help.