According to a report from VR-Zone, there will be issues with older or bargain power supplies, when you combine them with Intel's upcoming Haswell processors. The reason for these issues can be found with the optimized C6/C7 states and the minimum load requirement of the Shark Bay platform.
According to Intels announcement, chipzilla will show it's upcoming 4th generation Core processors during Computex on the 4th of June. Haswell will not only bring per MHz performance improvements, it will also feature new X86 and AVX2 instructions. Intel has also overworked the iGPU, which should now be significantly faster.


Trusting a report from VR-Zone we believe that Intels Shark Bay platform, on with Haswell will be running, needs power supplies that offer a minimum load supply of 0.05A on the CPU 12V2 rail. In other words that means 0.6 Watt. In this regard it's well possible, that older PSUs or bargain models won't be able to meet these specs. When an Intel Haswell CPU requests a C6/C7 power state, then the system becomes unstable, triggering UVP/OVP and causing a shutdown. Taking a look at the ATX12V v2.3 specs, which have been issued, when Ivy Bridge was released last year, shows that back then minimum load was 0.5A.

But what makes us worry the most is the fact, that not even manufacturers of high-end power supplies communicate the minimum load specs. Therefore it's simply impossible to compile a compatibility list.

Source: VR-Zone