• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

-5 v line

B

bob63

Limp Gawd
Joined
Nov 9, 2001
Messages
135
I'm trying to put togeather a HTPC system with a Silverstone LC-11 case, that includes a proprietary power supply (230 w pcf). I could not get the system to POST and tried the usual suspects, CPU, memory etc. I tried booting it up out side the case to avoid a potential short, but no dice there either. I treid a minimal config, just the CPU, one stick of mem and on board video but still no POST. I all the above cases the fans would spin up but the system would not POST. I then tried another power supply that I had laying around (generic 300W) and it POST'ed without a problem. I then tried connecting both power supplies to a PS tester that I have. On the proprietary PS there was a delay in the PG (ground) light coming on and the -5 volt light did not come on at all. With the genaric PS all the lights came on imeadiately. Going by the fact that the system posted with the generic but not the proprietary I'd say I've found the cause of my problems. My question though is what is the purpose of the -5V line. I was under the impression that it was not used anymore. I'm building the system with a Foxconn 865M01-G microATX board, so its a fairly recent board. Do some boards need the -5v and some not, or do they all need it. Swapping the PS is not an option as the LC-11 is a slimline HTPC case and only the propretary PS will fit.
 
The -5v line was taken out since the ATX12V 1.2/1.3 specification, so it could be perfectly normal for your psu not to have it.

The only recent use for the -5v that comes to mind is the MSI Neo4 SLI audio chip.
 
Eh. I guess I misread the ATX12V spec on formfactors.org. I suppose "Removed -5v reference" (2.01) meant the rail got removed, and not "Remove -5v from all power distribution tables" (1.2) or "Remove guidance for -5v rail" (1.3).
 
yup it was only with the last revision the actual -5V wire dissappeared from the connector ;)

just in time for MSI to get caught out :p
I also heard that the OCZ booster employed the -5V for the LED

other than those I know of no modern mobos or components\cards that still use it
all the way back to PCI\ISA mobos and thats truely ancient history
 
Ice Czar said:
actually its in the ATX12V v1.3 and 2.0 spec

it was dropped from the ATX12V v2.01 revision

last "real" use of that rail was for ISA slots
(why MSI used that chip is beyond me, sheer stupidity)
Click to expand...
What percentage of (ATX) PSUs which are currently being sold do not have a -5 V rail?

I'm actually not so surprised at MSI screwing up again, not after the bug in the CPU voltage regulator circuit in their KT133 and KT266-based mainboards.
 
most any dual +12V rail supply wont have the -5V
Neopower
OCZ 600
Seasonic S12s
Fortron Blue Storm


the ATX12V v1.3 hybrids still have it
all the Powerstreams except the 600W
the PCP&C 510s
Fortron 530 and older


Enermaxes vary since they have retained series names across the standards

the general rules would be if its dual rail it probably doesnt have -5v
while the AEX12V v2.0 spec added dual rails and still had the -5V
no one actually made those supplies before the next revision (v2.01) hit


I'll take this opportunity to spread the rumor that the next revision will add four more pins to the auxillary +12V mobo connector
bringing the spec into full EPS12V connector compliance (8pin from 4pin currently)

possibly even making the specs identical by having common plane 3 x +12V
or split plane 4 x +12V rails
that makes alot of sense to me considering where PCI-E has been heading
well at least for the common plane
 
You must log in or register to reply here.
Back
Top