This sucks - Switched from 300W to 400W Fortron and...

ARF!

I get lower 5v readings with my new PSU (FSP400-BNP) than I did with my 300W High Power!

Volts before:
+3.3 | 3.30
+5 | 4.89 - DMM reads 4.98
+12 | 12.64 - DMM reads same

Volts after:
+3.3 | 3.28
+5 | 4.76 - DMM reads 4.89
+12 | 12.03 - DMM reads same

This is with a lowered OC under load on the second, speed @ sig for the 1st. At the speed before the voltages were 4.70v

This is well below the rated wattage (~240W total used) and this thing is supposed to have 40A on the 5v rail - WHAT IS GOING ON??!?!

Are there any pots in Fortron 400W PSUs?

BTW I bought this "brand new" off Ebay, could I RMA it? Or at least return it to the seller?

Added stuff: I calculated the 5v line current draw to be around ~20A, and at this current the voltage is 4.76v. Increasing the draw to about 26A made the voltage drop even more to 4.65V - is this PSU worthy of the Fortron name? It ain't even up to ATX standards.

Blatantly going back to the seller if I have my way.

sounds like your system is stressing that psu the farther you o/c. maybe return it and get something else

Are those readings with a MultiMeter?

If not...use one. Motherboards are weird.

he said hes using a DMM and that is kinda edgy, but I doubt youll get a refund, Id either keep it and watch for hiccups or problems, and if Its unbearbale sell it on ebay and use your old one again.

The voltage isn't terrible but it's worse than I expect from a Fortron. There are two pots inside and I might twiddle those to see what happens.

The motherboard readings are just wacky, the AUX and ATX readings suggest a more sensible output.

At "normal" loading, about 20A on the 5v line, I gots 4.87v on the AUX connector and 4.83 on the ATX connector pins - I might try pot twiddling and contact cleaner on the plug...

How do I attach images?

L337 M33P said:

ARF!

I get lower 5v readings with my new PSU (FSP400-BNP) than I did with my 300W High Power!

Volts before:
+3.3 | 3.30
+5 | 4.89 - DMM reads 4.98
+12 | 12.64 - DMM reads same

Volts after:
+3.3 | 3.28
+5 | 4.76 - DMM reads 4.89
+12 | 12.03 - DMM reads same

This is with a lowered OC under load on the second, speed @ sig for the 1st. At the speed before the voltages were 4.70v

This is well below the rated wattage (~240W total used) and this thing is supposed to have 40A on the 5v rail - WHAT IS GOING ON??!?!

Are there any pots in Fortron 400W PSUs?

BTW I bought this "brand new" off Ebay, could I RMA it? Or at least return it to the seller?

Click to expand...

The voltages in your "Volts after:" column are still
within 5% of specs. Even a spike/drop of 7-8% shouldn't
cause problems.

The rails don't have to sit at exactly 5.0000v or 12.0000v
for stability.

I know that the voltages on the motherboard were in spec that test. Look further down and you will see that it sagged to 4.65v - but further testing with a DMM sez that the 5v was at 4.83 at the end of the ATX connector.

/me goes and gets some contact cleaner and a pot twiddler...

good luck

Ok, I took it to bits and we have some interesting findings...




There appears to be some oxidation on the ATX connectors. The bottom one is from the Fortron, the top is from my Sirtech, which is nice and shiny. I may need to clean those...



This is the first pot - on a little upright board the 3.3v sense wire comes into this thingy with an adjustable orange pot on it.




This is the second pot location - it is white and on the main board itself.

Now what I am asking is this: WHAT DOES EACH POT DO?!?!?!

I could be turning one that alters the "time to self destruct" for all I know, so which one is for the 5v line adjust?

Teh bumpy - someone must know

I think the other pot is for the +5V, but in my 300W Fortron there's a third pot on the other side of the heatsink that I think adjusts all the voltages together. IOW I think it's supposed to be adjusted to get the +12V right, and then the other pots trim the remaining positive voltages. All the adjustments are supposed to be done with loads all the way from minimum to maximum.

I was told to never use abrasives on the contacts because the plating on them is very thin, and the best thing is a chemical contact cleaner like De-Oxit.

Do you really need to adjust the voltages? 4.83V is only 3.4% below perfect, and to know if the 400W is sagging more than the 300W is by measuring both at minimum loads (minimum by PSU manufacturer specs or maybe with a 300 MHz CPU and a slow video card) and seeing how much they change with load.

Thanks for the reply

The voltage was 4.83 under ~240W of total load at the ATX connector and 4.76 under MBM readings, so the 5v line reading on the motherboard would be way out of spec if I cranked up anymore overclock from the one in rig#2 at the moment.

I am getting a chemical contact cleaner (heavy duty) to sort out the oxidation.

Under no load (400W Fortron) the 12v is surprisingly low - 11.47v and 5.10v with the 3.3v being fine. Bit odd that a mere 50% load (20A) caused the voltage to drop to 4.83v.

The 300W under the load of my system (rig2) in the sig was giving wacky voltages - the 5v line was sagging if I turned up the OC more, and this pushed the 12v line to 13v and above. The PSU was also starting to push hot air.

I have plotted graphs of a) varying load and the voltage at the AUX connector (effective PSU voltage) and b) the same varying load at the ATX connector. The graphs show that 1) there is some loss down the ATX wires, but not a lot and 2) the PSU voltage at 0% 5v load is ~5.10v and under 90% 5v load to be 4.55

I varied the load on the PSU by changing the CPU specs: - CPU at 1533MHz with 1.5, 1.6, 1.7 Vcore and 2091MHz with 1.5, 1.6, 1.7Vcore. I used benchtest.com's wattage calculator to find the change in wattage.

These extrapolations are confirmed at one end by the no-load readings, so are probably true at the other end of the spectrum. I will post the graphs when I get home.

Currently the PSU isn't causing my PC to screw up (yet) but when I get an SK7 and a SmartfanII I want to be able to crank it up without the Fortron falling to pieces. Which at the moment, is doing a far better job at it than my 300w.

Muahahah

Tweaked the pots, now the voltages are as follows:

3.3v = 3.28 as before
5v = 5.03 in MBM, 5.21 on the DMM at a molex
12v = 12.61 - 12.64 DMM

I can confirm that the White pot on the main board adjusts both the 5v and 12v rails. They both go up or they both go down.

The little orange pot adjusts the 3.3v line, but I left this unaltered.