Can a crappy psu slow the system down

[ddscentral]

A friend of mine asked to reinstall Windows because it was running slow. The system is: Celeron D 2.8Ghz (Prescott), 512MB RAM, Radeon 9550 Video, Maxtor 160GB HDD and a DVD drive. The mobo is ASRock P4V88+.
Even after I reinstalled Windows XP, the system is still running REALLY slow.
Ran Everest on that system to see the sensor readings.
The software shows that +12V rail is unstable, at 10.7 - 11.8V (Will measure these voltages with a DMM later, when I will finish reinstalling all software).
Can a crappy PSU slow the system down ?

[Fatal0E]

Re: Can a crappy psu slow the system down

I have seen many times gaming computers built with very nice power supplies that were just not enough for the job. The computers were stable but 3dmark and games had severe stuttering problems, these problems went away with a larger power supply, so I would say yes.

What I have seen lately for example are nice over clocked quad core systems with 9800 GTX or GTX 260's and decent 425-500w power supplies. Heavy skipping and stuttering in 3D. Replace them with a nice 650w and its silky
smooth.

Then on the other end of the spectrum are your poor gamers that lack sense and purchase a $300 SLI board and a 1 kilowatt power supply and then pair them with a cheap cpu and something like a 7300gt video card. "Someday I will get and second video card for SLI". LOL

[acstech]

Re: Can a crappy psu slow the system down

Get out your multimeter and measure it. It should be between 11.4v and 12.6v. I usually keep it closer to 12v than that. If it's outside that range, replace the PSU.

[ddscentral]

Re: Can a crappy psu slow the system down

Well, the software readings were way off. +12V is at around 11.8V when measured with a DMM. Not a surprise for me.
That system is old (warranty expired 2006) and has never been opened before because warranty stickers were intact.
So the problem is not PSU.

[PCBONEZ]

Re: Can a crappy psu slow the system down

Crappy caps in PSU -> Noise in power voltages
Noise in power voltages -> CPU, RAM, Video, Chipset, Controllers don't work right.
... -> Corrupted data signals

Any other questions?

[PCBONEZ]

Re: Can a crappy psu slow the system down

Software can't see noise.

[linuxguru]

Re: Can a crappy psu slow the system down

If there's significant ripple on +12v, a variety of subsystems can overheat, starting with the HDD. If there's significant ripple on +3.3v or +5v, the Northbridge could overheat. If there's a temperature sensor that picks up internal cabinet temperatures, the BIOS might use it to throttle down the core clock.

So, yes, a bad PSU with high ripple voltages on some rails can cause overheating, which could trigger clock throttling (lower system performance). But it's a straw-on-the-camel's back thing. I'd look for failing fans first if overheating is suspected.

[dood]

Re: Can a crappy psu slow the system down

Does the hard drive on this system thrash quite a bit? Those older Maxtor drives were never known to be speedy (or overly reliable). Perhaps upgrading to something with a bit more cache would help. That drive could even been a 5400rpm. What's the model of the drive?

[jpdoe]

Re: Can a crappy psu slow the system down

The #1 suspect when a PC is REALLY slow is the hard disk transfer mode.
Check it under SystemProperties/Hardware/DeviceManager/ATA-ATAPI-Controllers/IDE-First-Channel/AdvancedConfig/ActualTransferMode

This will likely read PIO, instead of UltraDMA.

[dood]

Re: Can a crappy psu slow the system down

Good point, jpdoe. And when it does read PIO (or a low UDMA number, like 1-3), it can mean several things.

1. Drive access method is being limited in the BIOS. Most BIOSes have the ability to restrict the IDE devices to PIO
2. Bad cable or bad drive causing read/write errors. When Windows detects a certain number of access errors (not sure what the threshold is), it will gradually reduce the UDMA mode to slow transfers down. So if your drive is ATA-100 (UDMA 5), it may step it down to 4... and then if there's still errors, drop it to 3, and so on... until it finally gets down to the slowest, PIO.

If it is in PIO mode, you can reset it to UDMA in the location jpdoe speficied above. Restart the PC, fiddle with it a bit, do a few more restarts, etc... and then see if it's still in the mode you set it to. If it's started reducing itself again, you know you've got trouble somewhere.

[acstech]

Re: Can a crappy psu slow the system down

Sometimes the event viewer will record disk errors. Might be worth a look.

[PCBONEZ]

Re: Can a crappy psu slow the system down

... shows that +12V rail is unstable, at 10.7 - 11.8V ...

-->> Can a crappy PSU slow the system down ?

~ YES ~

With +12v dipping to 10.7v your CPU and it's VRM are likely having problems.
[Drives too but if CPU power is hosed that doesn't matter much.]

ATX spec for +12v is +/- 5% which is 0.6v. [ 11.4-12.6 vdc ]

Max Ripple [noise] allowed on +12v is 120 mV peak-peak [0.12v p-p] which is exceeded quickly with bad caps in PSU and often 'crappy PSUs' are just barely [or aren't at all] within that spec in the first place.

Well designed motherboards can somewhat tolerate (compensate for) a marginal PSU [at least for noise] but an ASRock board does not fall in that category.

.

[ddscentral]

Re: Can a crappy psu slow the system down

The software reading was fake. I measured the actual voltage with a DMM when XP was running, and it was near 12V (Everest was showing 10.7 or 11v).
PSU is generic (some unknown brand) 350W, Model: 300x
Maxtor HDD is SATA, not IDE (didn't check if it's using IDE mode), and it's loud.
Will check the system with 350W FSP from my secondary computer to see if anything changes.

[ddscentral]

Re: Can a crappy psu slow the system down

Other psu did not help. It seems that the HDD is the only problem in this system.
Wrote down the hdd model: Maxtor 6L160M

[RJARRRPCGP]

Re: Can a crappy psu slow the system down

If there's significant ripple on +12v, a variety of subsystems can overheat, starting with the HDD. If there's significant ripple on +3.3v or +5v, the Northbridge could overheat. If there's a temperature sensor that picks up internal cabinet temperatures, the BIOS might use it to throttle down the core clock.

So, yes, a bad PSU with high ripple voltages on some rails can cause overheating, which could trigger clock throttling (lower system performance). But it's a straw-on-the-camel's back thing. I'd look for failing fans first if overheating is suspected.

Also I heard that newer Nvidia video cards throttle the video card when the Nvidia software sees a power drop and gives a message in a balloon or box that you don't have enough power and thus throttled your video card.