Pin mod to undervolt Pentium D 820 in Dell Dimension 5150C

wjdashwood · Post by **wjdashwood** » Thu Mar 09, 2006 2:57 am

I picked up a Dell Dimension 5150C for ï¿½370 for a friend yesterday. 2GB of DDR533, 160GB Samsung Spinpoint, Pentium D 2.8GHz dual core all in a tiny BTX case. Absolute bargain for him, even though there's not enough room for tinkering for me.

Anyway, the processor is kicking out so much heat that I really want to bring the VCore down a bit. I just ran CPU-Z and it detected the VCore as 3v!

Surely this can't be right? I was expecting 1.5V max so maybe it has something to do with the dual cores which is throwing CPU-Z of track. Or maybe the Dell just reports whatever it feels.

The sSpec is SL88T. Firstly, is there any way to find out what the VCore actually is? Secondly, can anyone figure out which pins need joining/breaking to bring the VCore down to something reasonable.

Here's the VID table (dead link removed) taken from page 16 of the data sheet. It's a nice easy mod on my Mobile Pentium 4M where you bend a pin at the edge to bring VCore down to 1.1v which allows me to run passive. I don't expect the same from this but it's giving out so much heat that I don't think it's operating at it's correct voltage in the first place.

jaganath · Post by **jaganath** » Thu Mar 09, 2006 3:50 am

I just ran CPU-Z and it detected the VCore as 3v! Surely this can't be right? I was expecting 1.5V max

The processor datasheet says max Vcc is 1.55V, so your expectation was more or less correct.

datasheet

page 19, section 2.5, table 2-2

As you say, the 3V Vcore may have something to do with the program detecting 2 x 1.55V.

Being a Dell, the chances of there being undervolt options in the BIOS is zero.

Try PC Wizard, see if it reports the same Vcore.

it's giving out so much heat that I don't think it's operating at it's correct voltage in the first place.

Well, it is a 95W TDP CPU. Of course if both cores ARE running at 3Vcore, the chip should have melted by now or thermal throttled.

wjdashwood · Post by **wjdashwood** » Thu Mar 09, 2006 3:53 am

Thanks for your input jaganath, I'll try PC Wizard. I don't think there's any way a cheap Dell mobo could supply 3v so I'm sure it's a misreading.

wjdashwood · Post by **wjdashwood** » Thu Mar 09, 2006 4:17 am

Couldn't see any VCore reporting in PC Wizard but as it's made by same people as CPU-Z I would guess they'd use the same code anyway.

jaganath · Post by **jaganath** » Thu Mar 09, 2006 5:13 am

Couldn't see any VCore reporting in PC Wizard

To see Vcore reporting you have to click on the icon for "Voltage, Temperature & Fans"; this is the icon at the bottom right of the 12 icons on the left of the screen shown here:

It's that little icon with the + and - signs above it.

wjdashwood · Post by **wjdashwood** » Thu Mar 09, 2006 12:36 pm

Sorry for the delay. I don't have those options on there, only the hard drive temp.