Has Your PC Become ...Real Slow... Lately ?. Dunno Why?

This is for folks who are running XP System on their PCs.

Your computer might be infected with spyware/malaware,

unstable power supply, faulty RAM, HD with bad sectors,

pagefile/hibernation files become too bloated, etc, etc.

If you have checked and it's none of that and your PC is

still teetering between life and death, then you might be

suffering from a unique problem, like myself.

Here's how you can check it out for yourself:

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01. Click on the My Computer icon on your desktop and

choose Properties.

02. Go to Hardware --> Device Manager.

03. Open IDE ATA/ATAPI Controllers :

There will be a Primary IDE Channel, and a Secondary IDE

Channel. Click on each of them, one-by-one, and choose

Properties.

04. Go to the Advanced Settings and check to see if the

Transfer Mode & Current Transfer Mode is PIO or DMA ?.

05. If it is PIO, switch it to DMA (if available). Repeat the

same procedure with the Secondary IDE Channel, switching

the Transfer modes from PIO to DMA. If you cannot do that,

you will have to disable the driver. When you reboot the OS

will auto find the driver and deploy the DMA mode.

06. Now reboot your computer.

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If you were on PIO (like I was for my Primary Channel), after

switching to DMA, you should see a marked improvement in

the stability of your PC. Actually, it is such an enormous improve-

ment that you'll think you just upgraded your computer.

I hope this helps out somebody out there. It really took some

doing to figure it out for myself.

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Sheikh 'P.S.A' Chilli

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PS: If somebody more familiar with this stuff can shed some

light on these two modes (PIO/DMA), it would be a great help.

^there is exponential decrease in the performance of windows OS according to microsoft..the only way to make them fast is reinstallation....the usual smooth tenure of XP is 9 months...

OK, after Google'ing a bit, it turns out that in most cases,

Windows will automatically downgrade your IDE access

method from DMA (Direct Memory Access) to PIO (slowest)

if your Windows IDE port driver "receives a cumulative total

of six time-out or cyclical redundancy check (CRC) errors...".*

If your PC has suffered the KESC load-shedding like myself,

several times/day, then it easily qualifies for the 6 cumulative

CRC checks. That's probably what chiefly contributed to it.

For more details check the Microsoft page here.

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Sheikh 'KESC Ka Kata' Chilli

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ref (*): http://support.microsoft.com/kb/817472

Duh!

Since SP2 and SP3, Windows XP will automatically try to use DMA mode for HDD (if it has correct drivers for controller).

wampyr, it states on the Microsoft Support page

that Windows will demote your PC from DMA to PIO,

if you have 6+ (cumulative ~ total) CRC checks.

I have SP2 and after repeated shut-offs due to load-

shedding, Windows started doing auto CRC checks. I

had DMA in my Transfer Mode, but was allotted PIO by

Windows in the Current Transfer Mode box.

I am sure the average PC user has no reason to know

about this little Windows sneaky maneuver.

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Sheikh 'Caveat' Chilli

[quote=", post:, topic:"]

wampyr, it states on the Microsoft Support page

that Windows will demote your PC from DMA to PIO,

if you have 6+ (cumulative ~ total) CRC checks.

I have SP2 and after repeated shut-offs due to load-

shedding, Windows started doing auto CRC checks. I

had DMA in my Transfer Mode, but was allotted PIO by

Windows in the Current Transfer Mode box.

I am sure the average PC user has no reason to know

about this little Windows sneaky maneuver.

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Sheikh ‘Caveat’ Chilli

[/quote]

On proper shutdown with (letting Windows to) properly clearing dirty bit on drive, won’t it automatically change Current Transfer Mode back to DMA on next (clean and without error) boot?

It didn't, for me wampyr. Not until I went in there

and changed it manually, myself.

They use the word "cumulative", which means if you

accumulate 6 CRC checks, you are auto downgraded to

PIO (for your own good), since you might have a vulnerable

HD, or other irregularities which in the high-speed DMA

mode (in their opinion), could corrupt the data on the HD.

They don't take into account the PEPCO situation down

here, of course. In the USA one can go a lifetime without

encountering a blackout in your area. There, such auto

downgrades make sense. Here, not so much.

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Sheikh 'Aik Lathi, Aik Bhains' Chilli

@sheikh_chilli

This is interesting.

In my experience, I have a PC (under my management) that acts as a (kind of) router (plus few more roles) and runs 24/7. It has no backup electricity. It goes off when WAPDA do blackout and automatically comes back to life when electricity returns. Means, no proper shutdown in last one year (since when I formatted and start running it). It has Windows XP SP3 and I just checked (over the network) and it is still using DMA transfer mode on both of its HDD.

In one year, both HDD got bad-sectors due to abrupt blackouts (both HDDs are second hand and I got them very cheap and they are near their end-life cycle). But still working on DMA transfer mode.

I used to think that it is maybe because I am using Microsoft's native HDD driver for controller. Both HDD are PATA 100 and both has NTFS format, with only one primary partition in each HDD.

[quote=", post:, topic:"]

PS: If somebody more familiar with this stuff can shed some

light on these two modes (PIO/DMA), it would be a great help.

[/quote]

I can explain DMA to you. In a computer system the fastest component is the CPU. Everything else is slower than it. The CPU is also the command and control authority and everything goes through it.

Now even though the other parts are slower than the CPU, the CPU needs them to do anything useful. It needs to load programs and data from the hard disk to actually have something to process. But the problem is that the hard disk, for instance, is an order of magnitude slower than the CPU so micro managing the transfer of data from the HDD to RAM is very time consuming for the CPU.

Direct Memory Access frees the CPU from managing this by allowing devices to directly access main memory. So the CPU just has to give the command to load data into memory and then it goes about its business processing other programs. When the HDD is done the DMA controller will issue an interrupt to alert the CPU that the data or programs have been placed in RAM and are available for processing.

From the Microsoft's KB article (that you have referenced):

http://support.microsoft.com/kb/817472

Quote from above article:

[quote=", post:, topic:"]
Windows XP

This problem was first corrected in Microsoft Windows XP Service Pack 2.

[/quote]

@sheikh_chilli

Dear, are you sure you are using SP2 or SP3?

Minus Some program in startup ..

write in run msconfig

I am using XP/SP2 and since there was some apprehension

(based upon history of initial releases by MS of it's security

patches) about the bugs not completely worked out in SP3,

I have held off employing the security patch 3.

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Sheikh 'Chaach' Chilli

Sheikh Sahib, SP3 is perfectly fine. :)

I am using it in all my PCs and at work.

I'm also using sp3, it is working fine. It is always using DMA mode

OK, so I d/l the SP3 patch and after I deployed

it the jittery, anxious, hyperactive, demented XP

system has suddenly turned into a cool, suave

and composed OS.

I thought maybe the P4 was done for and that's

why I was having all these problems. Guess not.

I am not sure if my problems with PIO/DMA are

solved, but in general, I would advise all of you to

take the plunge and put SP3 on your XP systems.

It's like a dose of sanity, to an otherwise wild 'n

rabid XP.

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Sheikh 'Relieved' Chilli

Sheikh Sahib welcome back to Windows :)

That's why they say always keep your Windows updated :)