Few PSUs i wouldn't try this on granted it is same as vcap mod.
1) PC&P 510 Dlx.
2) Enermax (pre noisetaker models)
I've had friend who would consistantly kill A64 memory controller doing it on above 2 PSU. He moved on to OCZ Powerstream and had no more dead FX-55 (well at least on memory controller). Zippy is another one that worked fine for months... where is my zippy now... hmmmm -_-;