Hey,

Previously I've ran a dual laptop psu build, but I just recently discovered the HFX EF28 and was wondering if this could power my whole rig:

Intel i3-3220
KFA2 GTX 660
Gigabyte GA-Z77M-MVP
2x DDR3 RAM
64GB SSD

According to the eXtreme Power supply calculator I'll be near 18.5A on the 12V rail... However I'm not entirely sure how accurate that is. The website for the EF28 says 15A on the 12V rail, however I cannot access the datasheet so I'm not sure if that peak or sustained. I plan on undervolting the 660 if that makes any difference.

The 12V rail is likely to be the weak point and the HFX PSU does not have a 6-pin PCI-E connector which means that it isn't really intended for high current draw on the 12V rail. You will have to use a 2 molex - PCI-E adaptor which should work OK.

Undervolting the 660 makes good sense as it's really the graphics card which will be the problem.

I'm assuming this is for a system where an internal PSU is not possible.

Just in case anyone else is interested. I bought a simple socket power monitor and ran some tests on my current system (i.e. without the GTX660). At stock settings the full system consumes a peak of 59.8W running Intel Burn Test from the wall.... setting the VCORE to 0.92V I get a peak of 53.6W. I'm guessing with a DGPU I could probably undervolt further since only the screen messes up when it gets unstable.... however there wouldn't be much point (from a peak power perspective, you would get better temps) since the motherboard only changes the highest VID and at 0.92V it's already lower than the 2nd highest VID. At idle it consumes 21.3W.

The 12V 120W laptop power supply I'm using happens to be the same used for the Butterfly Labs Single bitcoin miner and someone has measured it to be ~84% efficient with a load of 85W (71% Load). Therefore assuming the same efficiency @ 45% load the psu is outputting 45W when undervolted which leaves me with 155W for the GTX660. Most reviews put the GTX660 under load power consumption about 110W so, theoretically, I should have plenty enough head room with the HFX EF28 or a 12V 192W laptop PSU.

I did obtain slightly higher power consumption (61.8W and 55.4W) by taxing the GPU and CPU with the dolphin emulator but when I install my DGPU there probably won't be much load on the IGPU.... although I do plan on trying VirtuMVP.

I've been useing the EF28 to power the system in my sig since 2007, which would use much more power - 5750GPU, old Q9300CPU and 2 HDD! I haven't stressed the GPU on purpose but I have run it with prime95 at 100% cpu and with my audio software fully loaded. No problems, no coil whine, no reason to think it's going to give up soon. I'm going to re-use it in my next system soon I think.