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"EZ-Plug" and low Wattage not good for P4 overclocks - Power Supply is VERY Important!

J

jiffylube1024

Diamond Member
I just replaced my old 300W Power Supply (without the special 4-pin connector for P4's) with an Enermax 350W one. What a difference that made! Before, my 12 volt rail sat at about 11.1-11.3V all the time (MBM5 readings). Now, the lowest it gets is 11.7V. The core voltage actually runs at or .01 above what I set it to, whereas before it was always .01-.02 below. Most importantly, I can run the machine at 2.4 GHz (stably too) at 1.65 or 1.675V, which was impossible before (2.25 was the highest practical setting before). I'm using a P4 1.8A on a P4B266 btw.

I was using the ASUS "EZ-plug" on the motherboard which uses a regular hard drive/device 4-pin connector instead of the special square-shaped P4 one (I didnt have the connector on my old PS). Note, this connector (the "EZ-plug") is for convenience and compatibility, but if you really want to push your chip (and comply to Intel's P4 specs) the square P4 connector is the way to go. I'm posting this to inform any people having trouble overclocking their P4's that if they aren't using the P4 connector, then that is quite possibly the problem; without it the chip cant get enough current. Also, this explains the low voltages recorded in MBM5, etc...

I figure a newer 300W PS with the P4 connector should be fine also; I just wanted to pass on my findings to everyone.
 
Just to let you know, I wasn't able to run my crucial over 140FSB untill I upgraded my PSU from a generic 300 watt to an antec 400 watt. Now it's stable at 172. Haven't tried higher, but It's amazing ram anyway. PSU is VERY important.
 
My 300w Antec's 12v is running at 12.043. It's not using the square connecter because it's an older model...
 
I have my 1.6A @ 2.5(156fsb) stable using the Easy-Plug on an Asus P4B266 with an Antec 300W PSU. Vcore is exactly what I set it at, 1.575V in MBM5. The 12V rail is always low, about 11.4V. Ram is Crucial PC2100 256Mb set at 2.6V.

While I agree that the PSU is an important component, a low 12V rail doesn't always translate into poor o/c results. I think I just got a realy good chip though, as most people can't reach 2.5 with only 1.575V, if they reach 2.5 at all. Maybe my system is just very forgiving.

Good info never the less Jiffy😀
 


<< While I agree that the PSU is an important component, a low 12V rail doesn't always translate into poor o/c results. I think I just got a realy good chip though, as most people can't reach 2.5 with only 1.575V, if they reach 2.5 at all. Maybe my system is just very forgiving. >>



Yeah your chip is killer! 2.5 GHz @ 1.575 Volts is insane! Mine can do that (barely) @ 1.70! Since you don't need much voltage to keep that chip stable, it appears a lower 12V rail doesn't phase that CPU either!



<< Good info never the less Jiffy >>



No problem. I hope it clears up confusion/helps everyone figure out how to o/c the P4 without problems 🙂.
 


<< Try using MBM 5. Asus Probe generally isn't very accurate (certainly not about temperatures). >>



Whether I use MBM5 or Asus Probe they both show the same temp at full load(Probe seems to be stuck at 40c till a it goes over 40c).I think Probe gives more accurate voltage readings because MBM5 shows my + and - 12v way low even with a brand new Antec PP412X.The -12v shows -1.4v and this computer wouldn't be running if it was that low :Q
 
[/i] >>

Whether I use MBM5 or Asus Probe they both show the same temp at full load(Probe seems to be stuck at 40c till a it goes over 40c).I think Probe gives more accurate voltage readings because MBM5 shows my + and - 12v way low even with a brand new Antec PP412X.The -12v shows -1.4v and this computer wouldn't be running if it was that low [/i] >>



I'm not sure what the any of the - voltages mean (-5, -12, etc) in MBM5, but I believe the + voltages to be more accurate than Asus Probe. Either way I got a tangible improvement from getting a new PS (And not using the "EZ-plug") and that's the point I'm trying to get across.

Btw, Asus probe gives me a constant 12.352 reading, whereas MBM5 fluctuates from 11.67-11.81 or so depending on load.
 
Well, I don't claim to be an electrical expert. But I think the 5v rail supplies current directly for the cpu voltage. I use an Antec 400-watt with adjustable pots. My 5v rail runs rock steady at 5.1v under full load. 12-volt reading is 12.7v.
 


<< But I think the 5v rail supplies current directly for the cpu voltage >>



I'm not sure of that because I know the square 4-pin adaptor for P4's is a supplementary 12V line.
 
My 5v rail only fluctuates from 5.27 to 5.19, but my 12v rail fluctuates from 11.55 to 11.92 and I am really not pushing it right now as I wait for my new supply to arrive. I am running at only 132fsb (so I can run my Crucial DDR2100 at 3:4 for 176) and my vcore at 1.55. Heck I wish I had caved for the 1.8A so I could use 132fsb (using 3:4 timing) and still be just below 2.4ghz.

Anyway with my vcore at 1.75 my 12v rail was bottoming out at 11.31 (too low for me, thats why I backed off). I don't think running your rail that far past tolerance could possibly be good for it. How bummed would I be if my supply cooked and fried everything that was connected to it. Needed a supply to put my wifes system together with anyway.........🙂
 
update Although i saw a major voltage increase across the board, still no OC success on an Asus P4B266-C, 105mhz fsb max, a very sorry 1800@1890
 
Warcon, you are running an athlon!!! the athlon draws from the 3.3v or 5v rail, while the p4 draws from the 12v rail...look at a p4 mobo manual and you will see what I am explaining...
 
Acanthus - try upping the core voltage to 1.60 - 1.65 . The most stable configuration (100% stable) is 2.25 GHz for me ... I run my 1.8A @ 125 FSB for 2.25 GHz @ 1.60 Volts. If not you might have to try 1.7V
 
I was running an Athlon, now I am running a 1.6A in a P4B266-C. Maybe you are looking at Rogue's setup...........😀 (Same picture) I know this thing is draining my 12V and leaves my 5V alone (which sucks because I have ample 5V current with my Enermax.............🙁

......................edit...............................
My reply to was to Rogue's comment about the 5v rail also. It was an example for him to see which one was being used. And with my Athlon my 12v rail was 12.54 typically, so it wasn't being used for much besides peripherals with my KT7A.
 
My 12v stays VERY tight with a "generic" power supply. It's a Top Power AMD/P4 cert 420w PS with the 12v square, cpu line. My 12 volt goes from 11.968 to 12.032 under heavy cpu load (SETI) on my oc'd Northwood 1.8a@2340. Core voltage is set to 1.650v, steady as a rock. I can do 2.40 and higher, but I'm waiting until freakin asus fixes this core temp reporting error.

How they can release a mobo with such a obvious problem is beyond me.
:|
 


<< My 12v stays VERY tight with a "generic" power supply. It's a Top Power AMD/P4 cert 420w PS with the 12v square, cpu line. My 12 volt goes from 11.968 to 12.032 under heavy cpu load >>

I've heard others mention the same good results with that PSU. I just purchased one from Directron for $49.00 + shipping (It's listed as a Directron Silent TT-400SS ). If it's as good as others say it is then that's a great deal.
 
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