upon downloading files and installation, i continually get "CRC" errors. i'm asking some computer friends and they say that the memory might be bad. also, when i go to a page with images, many of them become "corrupt" and don't display right: i.e. there are some chunks of the image that just don't show up.
does anyone have any advice on how to fix this? do i need to tune any memory settings in the bios?
CRC errors are cyclic redundancy checks. That typically points to an error in a data packet or some other form of data that was transmitted.
Does this happen everywhere or just on the internet? If its just on the 'net, then you might want to check your ethernet drivers and protocols. Try pinging and make sure you're not losing packets, etc.
If its local on your computer, you probably have a hardware issue.
If I remember right from my networking class 3-4yrs ago, the CRC is calculated by the transmission of a division equation, basically they say divide x/y and the remainder is R. Then R is tagged into the CRC part of the data packet and it compared to insure data integrity.
it seems to only be happening on the internet. i'll have to check any i/o through the dvd rom drive. i did a ping on some sites and didn't have any real issues with lost packets. they all turned up 100%.
i did read about the issues people were having with the built in nvidia firewall so i turned it off. i still get errors on downloads.
i especially interested in downloading the windows xp sp2 file from their it section. however, i am never able to get a "valid" file. when i check the file properties/digital signature...it says "not valid".
and still, when i look at photo albums, there are some files that will have the "strips" of green, etc.
When you download files they are stored in RAM (OS WriteBack DiskCache) before being written to the HDD. Thus if your RAM is bad you will get CRC errors during the extraction of compressed data. eg: Installation programs, ZIP, RAR, etc files downloaded from the Internet.
The CRC errors are occuring when you extract / install the download files right ?
The CRC data (in this case) is stored inside the ZIP, RAR, Installation packages most the time, and is recalculated / checked when data is extracted to ensure it is not corrupt. Athough CRC (and other similar checks, like MD5, etc) is used for many things in computers to assist detecting faults. Some are also used for encryption.
CRC errors on a TCP/IP network are far less likely to be noticed by someone building their 1st PC, as if a packet is corrupted in transit it justs get resent. (Only if your network is totally stuffed will no packets get through)..... Once the data gets from the NIC to the PC/OS it is stored in RAM - This is likely where the fault lies (as you can download a file, but once downloaded it is corrupt).
You need to test your RAM, to isolate the fault, and possibly correct the timings manually, then perhaps flashing the BIOS (when you are 100% certain the memory is working, not before) wouldn't be such a bad idea.
Also don't "play" with the timings because someone tells you lower is faster, or higher clocked is faster. If you don't know exactly what a BIOS option does, leave it alone..... at least until you are well read up on it.
Tools to help isolate the fault:
http://www.sisoftware.co.uk - SiSoft SANDRA has a memory benchmark that isn't too bad at "detecting" bad memory. Just turn off the "Use 50% memory only option during testing"
http://www.google.com "Prime95" is also quite good at assisting to isolate faulty RAM so long as the right options are used.
The above tools are mostly useful for isolating faults to RAM.
There is a slim chance it could be HDD related, or HDD cable related, or even chipset / driver related, <- if you didn't install them, and not RAM related. However HDD failures are more noticable, even to the rookie, and faulty RAM / incorrect configuration of RAM is far more likely.
You could try underclocking the RAM (and CPU), and/or turning off AI NOS, (and any and all other BIOS dynamic overclocking options Asus boards have - consult the manual for info on how to disable each one), and/or reducing the RAM timings to the slowest setting (3-3-3-8 should work with that RAM I think), and try 2T Command Rate.
Then gradually decrease the timings (should be marked on the sticks anyway) and see if instability returns. Do not use your OS to test for instability (as it may corrupt the registry), instead use / boot from a MemTest86+ floppy or CD-R.
Once you have the system stable reinstall your OS (Windows XP) and start from scratch. Anything you have downloaded is potentially corrupt, the larger the file the more likely it is corrupt... so consider logging them all up, deleting them all, then downloading again.
Welcome to the world of computer hardware btw -
Generally speaking, Asus 1.00 BIOS defaults are very aggresive, as it makes them look better in reviews / benchmarks, (which boosts their sales), then their 1.02 or 1.05 BIOS changes the defaults to more 'normal' levels and 'fix the bugs' [cough]. MSI used to be similar when their CoreCell came out, but they don't turn dangerous options on by default.
Before Asus, MSI and others had AI NOS, PEG Link Mode, Aggro RAM timings, and various other dynamic overclock options (some on by factory BIOS 1.0 default) I used to like them. Although as I am aware of the issues going back to them if need be won't cause much heartache. I've never had a major issue with their (or anyone elses) boards btw, just a few default settings and how the defaults 'change' when flashing to a new BIOS.
If you can not get it working the RAM or Mainboard might actually be faulty. However if the system was assembled DIY style then the shop, or shops, can indicate the RAM, Mobo, etc was working before it left the shop and only became faulty when installed DIY style. (By someone other than one of their own techs). Depends on how nice the shop(s) are, you may need to RMA the faulty component(s), if any, yourself.
Cross your fingers it is just a setting (or settings) in the BIOS.
thanks for the help! i ran the memtest86 and didn't run into any errors. i did only run it for about an hour though. should i be running it longer and have it cycle through more of the tests?
i also did a scan disk on the drive. it found no errors.
what i did notice (could have been coincidence) was that when i swapped dsl modems, it seemed to have *less* corrupted downloads. however, i still occasionaly get corrupted files, though only after downloading from the internet.
as for the bios, i have the asus a8n-e board and updated the bios to the "1010" revision. it might have helped slightly, but i still have download problems, which of course is unacceptable.
Note: This is all assuming HDD and Network cables are OK btw.
Run MemTest86 / 86+ in extended mode overnight with all tests, except the FADE test, which 86+ skips by default anyway. It will loop until interupted and just list errors.
It is good for 'burning in' memory aswell. Maybe you got a few intermittent memory errors but after using the system for extended period of time they have reduced to 0, or near 0.
Test #5 and #8 are the best ones to run if you are short on time though. If it lists any errors (especially consistantly between iterations), let it burn in for awhile, see if it can do 2 iterations in a row with 0 failures.
If it can do 2 passes in a row each with 0 errors, then running (Start, Run, "SFC /SCANONCE") from Windows XP then rebooting will likely reinstall anything corrupted and get you ~95% good again. Then re-install any mainboard chipset (eg: nForce4 drivers), video and sound drivers (in that order, rebooting between each one), and also uninstall / re-install your Network Card Drivers, etc.
Then run a "netsh int ip reset c:resetlog.txt" which will reset the TCP/IP in Windows XP and setup your TCP/IP settings again from scratch.
That is almost as good as re-installing Windows XP, without actually doing a re-install.
Any issues after that, then you guessed it, re-install Windows XP.
In '70s and 80's systems would need to be burned in for a full week before one would Quality Assurance 'Pass' them. Otherwise they'd have 10x the problems you've had in just a few days in the first day of use alone.
These days most components are sort of 'pre-burned' after manufacturing, and 19/20 times you can just Plug'n'Play (so to speak), but 1/20 it is more like Plug'n'Pray instead, if you get my gist. .
If the memory won't do 2 passes with 0 errors I would return it though. Assuming all other settings (BIOS, etc) are correct. Can always try +0.1 volts to VDIMM anyway, as a last ditch before returning it. (Assuming it keeps getting 1 or more errors on each pass).
Also FarCry is an excellent memory testing application, it can 'fail' from faulty memory faster than Prime95 can detect a fault in just an hour or two of game play. (Sometimes minutes it all it takes, depends if it is timings, or just a bung bit in memory at an address that is rarely used and hard to recreate faults on, but thats what MemTest86 and Prime95 are for. You can run them in your sleep. )
I just remembered the Prime95 settings to use aswell, to save time... 'Torture Test in Blend Mode', all the other combiniations in Prime95 are less geared towards hammering RAM. If need be run 2 Prime95 processes at once, each with 51% memory so there is some overlap and paging is forced (better safe than sorry).