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**SteveC** · 13 March 2002, 17:12

Ack! my 3.3 is now at 3.02V and my 12V at 13.02V! and the screen's flickering again

Close Seti@Home and my 3.3V shoots up to 3.39 and the 12V back down to 12.6V

Is my CPU dying?

**Wombat** · 13 March 2002, 17:45

CPU isn't the first place I'd look, but how high do you have the voltage on it? What is the temp? As long as it's not consuming an insane wattage, you should be fine.

Still, it looks like that PS might not be enough, because something is dropping your 3.3 What's your 5V line doing when SETI is on?

It could be the power bus on the MB is too weak, but let's hope not. You don't have any fans plugged into the motherboard, do you? That's the first way to relieve strain. Second, you could try downclocking your CPU, at least temporarily.

Try leaving the fans unpowered for a moment, and/or some drives. If this gets rid of your flicker, then it pushes the problem back to a weak PS.

My Fortran/Source (sometimes Sparkle) is a 350W that has 220W combined, and I've never had a power problem.

**Marshmallowman** · 13 March 2002, 18:10

I get similar voltages on my computer (also an 8kta3)
but they don't vary much...hows your mains power like do you get brown outs?

**SteveC** · 13 March 2002, 18:13

Hi Wombat,

Originally posted by Wombat
CPU isn't the first place I'd look, but how high do you have the voltage on it? What is the temp? As long as it's not consuming an insane wattage, you should be fine.

I doubt it's the CPU too - my old 300W Macron PSU never had a problem (until the other day when it just flat out refused to turn on)

The chips temp: ~47'C Full load. It's at 2Volts

Still, it looks like that PS might not be enough, because something is dropping your 3.3 What's your 5V line doing when SETI is on?

Dropping from just under 4.9 to ~4.8

It could be the power bus on the MB is too weak, but let's hope not. You don't have any fans plugged into the motherboard, do you? That's the first way to relieve strain. Second, you could try downclocking your CPU, at least temporarily.

I have got 2 80mm fans, plus the 60mm one on the mb headers. But fans are 12V, so it doesn't matter?

Try leaving the fans unpowered for a moment, and/or some drives. If this gets rid of your flicker, then it pushes the problem back to a weak PS.

Do CDROMs/CDRW take much power when they're not doing anything? If anything, they'll only effect the 12V and 5V lines anyway, surely? I though the 3.3V is only onboard the motherboard.

My Fortran/Source (sometimes Sparkle) is a 350W that has 220W combined, and I've never had a power problem.

Might borrow an enermax tomorrow.

Weird - I've just started SETI up again, and now no flickering and my 3.3 is as 3.39V????? I dunny understandy!

EDIT: there it goes! 3.3 back down to 2.93V, 12V over 13 & screen flicker. Close SETI, instantly back to normal.

Marshmallowman - I'm running on 1400VA APC SmartUPS. (I'm splitting one of the power outputs though to the PC, monitor & router - that's OK isn't it? The overall load on the UPS is only the 1st LED out of the 5.

**Greebe** · 13 March 2002, 18:28

OK with the core set to 2.00v your pulling 89.5 watts peak... that's an aweful lot... more than a stock Tbird @ 1.4gHz (~72 watts peak)... better scale up to a PS that can handle a much heavier load

**Greebe** · 13 March 2002, 18:44

actually second thought... I'm leaning toward the problem being the MB... everyone knows how I love to blaim caps, but this is the most common part to give problems just like this. Push them to their limit long enough and they will start to flake out and eventually fail. Please stop it before it does or it can kill the CPU and or other componets.

**Wombat** · 13 March 2002, 18:45

Let's see, you're running a 50W part up at 90W (doh, greebe posted that first).

I would pull the fans off the MB and onto 4-pin adapters, at least to troubleshoot. I have seen fans on the MB cause instability in the past.

About the drives, you're right that they don't take 3.3V, but it still comes from the same power supply. Seeing the 12V line jump like that, it looks like you're pushing the PS to the limit. Any reduction in draw is likely to lessen your problem.

The delay before your 3.3V line drops is kind of interesting. Sounds like either the filtering caps on the MB or the caps in the PS (more likely) can cover for you for a little while.

Marsh has a good point though. What exactly does the flickering on your monitor look like? Can you get the monitor and the computer on different circuits? There's a chance (outside my area of expertise, but probably not that likely anyway) that the PS is throwing some nasty noise back on the line, and your monitor is picking it up. Odds are, it doesn't filter from one "output" to another.

**Wombat** · 13 March 2002, 18:47

Mike, why would bad MB caps push his 12V up?

**SteveC** · 13 March 2002, 18:47

This is the 2nd PSU to do this. The first was an old (but trusty!) 250W. Going to knock the CPU back down a bit now.

**Greebe** · 13 March 2002, 18:58

Actually Rob each output is filtered seperately, but.. and this is a biggie... normally there are two major voltages produced from most switching supplies (-12vdc and +12) and from them the rest are derived. Hence once, lets say this is a cap on the MB, starts to fail it will induce a high (relatively speaking) frequency noise (commonly called hash) that is induced back into all the other voltage derived from it's respective voltage rail. Even tho there is filtering this is way more than the filters can handle and thus you come up with a problem just like Steve is seeing.

This is also why he's seeing two voltages going low while the main is going high (nature of the switching regulator beast.. main trying to keep up with the load imposed on it.

**SteveC** · 13 March 2002, 18:59

Now back at 1Ghz, CPU@ Default voltage (MBM reads 1.80V).

No SETI:

3.3V = 3.39V
5.0V = 4.98V
12.0V = 12.31V

CPU Temp = 31'C

So far so good.

Now loading Seti

**SteveC** · 13 March 2002, 19:06

So far, so good still!

With Seti for 5 mins or so:

3.3V - 3.39V
5V - 4.95V
12V - 12.43V

CPU still 1.80V, and temp only 32'C (it's cold in here, plus it's got a zalman flower with a 80mm fan stuck on the side of it!)

**SteveC** · 13 March 2002, 19:18

And 5 mins of prime95 no difference

This current 300W PSU gives 25A on the 5V line, my old 250W also gave 25A on the 5V line

but looking at the specs, my old Macron 300W that worked fine before had 30A on the 5V line.

I know the 5V line is the most important on the Epox 8K7A(+) cos it derives the 3.3v from it and doesn't use the PSU's 3.3v.

Looks like I will get yet another PSU, the enermax 350W gives up to 32A on the 5V line so that looks like a good choice. I know someone I can borrow it from too to check it works before I buy one.

Thanks guys!

**SteveC** · 15 March 2002, 12:11

Hurrah!

Currently at 1400Mhz, CPU @ 2.08V, all drives/fans going and <B>no flickering!</B> Even with SETI@Home running

3.3 is 3.39V
5.0 is 4.76V
12. is 12.37V

How? An Enermax 350W PSU

CPU has reached 51'C though

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