Try to keep Panaflo L1A at or above 7V re fan start,
or use the NMB 15dB(A) fans which are as-quiet/quieter.
The ATX 2.03 right back to original PC spec:
o PCs co-locate the case/CPU/PSU cooling to the 1 PSU fan
---- reason is misers re cost/margins & 1-field-replaceable-unit
---- plus arguably similar obsolescence & failure curves
o So PSU fans must supply cfm *beyond* their own needs
---- generally this is 35cfm for continuous full-load under 40oC ambient
---- clearly ambient will be even higher after dragged thro a case
---- and continuous load is beyond most PSU components anyway *smile*
So if you distribute load across several quieter fans external to the PSU,
then you can reduce the PSU fan speed beyond normal quiet-fan fitment.
The dB(A) figures are not accumulate, but weighted.
o You have 1x 37dB(A) fan & 1x 21dB(A) fan (typical PC PSU & L1A)
---- your gross dB(A) is now 37.10dB(A)
o You change to 2x 21dB(A) fans (L1A)
---- your gross dB(A) is now 24dB(A)
o You change to 1x 21dB(A) fan & 1x 15dB(A) fan (L1A & NMB)
---- your gross dB(A) is now 22dB(A)
o You change to 2x 15dB(A) fans (NMB)
---- your gross dB(A) is now 18dB(A)
So if a typical 400W modern PSU with once 37dB(A) and 35cfm has
a L1A fitted of 21dB(A) & 24cfm and a case fan of 21dB(A) & 24cfm,
the system airflow has gone up to 48cfm & noise level down to 24dB(A).
The reason some ATX specs suggested drawing cool air INTO the PSU
rather than exhausting it FROM the PSU, was to allow cooler air to be
brought in - so allowing quieter fans to be used and very importantly
to get away with a design which still used just the PSU fan in most cases.
You could make it work with P3/P4, but AMD aren't suited to this idea.
--
Dorothy Bradbury
www.stores.ebay.co.uk/panaflofan
Panaflo L1A in stock at 5.89ukp
NMB 15dB(A) & 18cfm in stock at 4.99ukp; 60, 92mm & 120mm fans in stock