330W or 660W AC Adapter for 980M SLI

I'm considering a Eurocom X8 with 980M SLI and the sales rep I'm talking to says I'll need a 660W AC adapter instead of a 330W adapter for 980M SLI. I understand that SLI consumes extra power but both the MSI GT80 and the Sager NP9377 with 980M SLI from xoticpc.com come with 330W AC adapters, without an option for a 660W AC adapter. Is there any reason why? Should I spend the extra $245 for the 660W AC adapter or will the 330W AC adapter be sufficient for 980M SLI? Thanks.

 

330 watt should be enough

 

330W more than sufficient. Scroll down to bottom of this review for power draw: http://forum.notebookreview.com/thr...-p377sm-a-with-980m-sli-review-update.764790/

Even with an overclock, max power draw from the wall was less than 310W, equating to less than 290W actual power draw.

 

You only need 660W if you're doing @Mr. Fox level benchmarking while overclocked and overvolted

 

@Steven Mal - I think the sales rep is probably looking to ensure your experience is a positive one. Better to have what you need than to be frustrated later on and wish you had been told differently. If you play games and run everything stock, you can get by just fine with a single 330W AC adapter. What CPU are you considering in the build, as that will also come into play. A 4930MX with a nice overclock can easily suck down 130W all by itself. Also, what is your intended use? Just playing games, or impressive overclocked benching fun as well? The latter changes everything... massively. If the latter is true, listen to your sales rep.

If you stay within the confines of the stock vBIOS, which is limited to +135 core offset and no more than a 25mV bump (1.025V max) you can make do with 330W. It will be adequate, but it's near the edge with +135 core overclock and a CPU running with a moderate overclock (say 4.o-4.1GHz). If you start pushing an unlocked CPU (mobile Extreme, K or X) to 4.3GHz or higher, along with a modded vBIOS and more than that +135 and 1.025V bump, you can kiss overclocking goodbye with a single 330W AC adapter. It will swiftly become woefully inadequate. Dual 330W are just barely adequate with meaningful CPU and GPU overclocking, as I can easily pull 600W with 780M SLI in my M18xR2 and as much as 675W with 980M SLI in my P570WM.

There is no down side to having the dual 330W setup available and readily at your disposal unless the extra cost makes the price of the system beyond your means. If you need it, you have it. If you don't, you've got a spare AC adapter, which always comes in handy if you use the laptop in more than one location. Running the dual AC adapter setup even when you don't need to, both of them will have an easier job sharing the load 50/50.

 

Ok, thank you. Right now I'm considering the Eurocom X8 configured with

120Hz display
CPU: i7-4710MQ OR i7-4810MQ
GPU: GTX 980M SLI
16 GB RAM
SSD: Micron/Crucial M500 480GB
HDD: 1TB 7200rpm

I've never overclocked before and I don't plan on it but I want to make use of my 980M SLI so do I NEED to spend the extra $245, if I'm not going to be overclocking? I've never used a dual AC adapter either. I'll probably end up getting the 660W but I just want to be sure.

TLDR: How would the system perform with a 330W AC adapter?