New video card (Radeon HD 4850) not working without the old one plugged in too

By craig83
Nov 9, 2010
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  1. Hey, just joined the forums because I have a slight problem with my computer.

    I recently upgraded my motherboard and graphics card and for some reason the new card won't work without my old one in one of the spare pci-e slots which isn't major but I was kind of hoping to sell the old graphics card on ebay as I didn't think I'd need it.

    Not sure how much it'll help but I upgraded to a Asus PQ5 deluxe mobo and with the new graphics card not coming right away I installed my old ati 2400HD card.

    Sooo, new graphics card came, Radeon HD 4850 and I uninstalled the last card (drivers, ati ccc), took it out and put my new one in. Rebooted and got nothing apart from being slightly miffed.

    So for some reason I put my old one in one of the spare slots, rebooted and everything is fine, installed new drivers etc and the system is even picking up the the old card is there still but is using the newer one.

    Just wondering if anyone had any ideas because it's slightly annoying and one problem it does bring up is that I can't use the boot up screen that comes along with the awesome new motherboard

    Any ideas would be welcome thanks.


    Motherboard: Asus PQ5 deluxe
    CPU: Intel core 2 quad Q6600 @2.40GHz
    RAM 2X2 Gig sticks, same brand.

    Video Card: ATI Radeon HD 4850 (Main) and Radeon 2400HD (unused, but needed or the 4850 won't work)

    PSU:CIT 750W Dual 12V Rail 12cm Fan PSU

    Monitor (connection used): Standard LCD monitor, VGA cable connecting to 4850 HD card via dvi adapter
    Hard drives: 1X500gb sata 1X1TB sata
    Optical Drives: 1X DVD reader writer (not sure what brand)
    Additional PCI cards: None
    Number of fans present: 2 X 120MM, 1 front intake, one rear exhaust. 1 X 80 mm side intake fan.

    StarTech 95mm Socket 775 CPU Cooler Fan with Heatsink

    Operating System : Windows XP 32 bit SP3
    Video Card Drivers in Use ( and tried ): used a file named 10-10_xp32_dd_ccc_enu from the ATI website.
    Motherboard Drivers Used: Standard on the disk that came with the motherboard.
    Apps/Games causing issues ( and if they've been patched ): Apps and games working fine apart from not being able to use the Express gate ap that comes with the motherboard
    All major components check 100% after thorough testing ( eg. Memory & Memtest86 ): All components working fine before the new graphics card.
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,233   +234

    Are these video cards PCIe? Can you swap video slots with the 2 cards one at a time, and still get the video to work? Have you played with the bios and checked the video settings and allocations?
  3. craig83

    craig83 TS Rookie Topic Starter

    Both are PCIe, only difference being is the old one doesn't need a power source, tried taking the old one out of the secondary PCIe slot and the new one in the primary slot doesn't work...

    Tried flicking through the bios and there doesn't seem to be any options linking to the PCIe ports.

    I know the new card works too because I've been using it to play New Vegas on max settings etc, it's just frustrating as to why it won't work without the old one in the second port.

    Thanks for the help :)
  4. klepto12

    klepto12 TechSpot Paladin Posts: 1,115   +9

    you might try a program like driver sweeper and clean all the ati drivers and then put the card in.
  5. craig83

    craig83 TS Rookie Topic Starter

    Ok, well I tried something and nearly fried my card in the process, luckily it's still working.

    I tried the card in a lower pci-e slot, on its own and it worked, only downside being is I don't have enough room in my case and it couldn't breath, I got all happy, smelt burning and my puter died and I burnt myself taking the damn card out which was hot as hell lol.

    So I know the card works, I know the monitor with the card works, but the card won't work on its own in the main pci-e slot...

    and also looking around the bios there is no option to engage the first pci-e slot before the others so I'm all out of ideas!
  6. klepto12

    klepto12 TechSpot Paladin Posts: 1,115   +9

    have you tried both video plugs on the back of the card?
  7. craig83

    craig83 TS Rookie Topic Starter

    yup, also tried in the bios to check if it was peg/pci startup which it was already, tried the other setting which didn't work either.

    One thing I was wondering, I hooked up the 24 pin power and also have an 8 pin connection at the top of the board, my PSU only came with the 24 pin and a 4 pin one leaving the 8 pin one halved and asus put a removable cap over half of the 8 pin one.

    Could that have anything to do with it? Like if I got a decent PSU that had the 24 pin and 8 pin connectors would/should that make a difference?

    thanks for the help :)
  8. klepto12

    klepto12 TechSpot Paladin Posts: 1,115   +9

    it could be that u need the 8 pin to supply the extra power your card needs coming from the 16x slot but your psu should have the 8 pin are you sure there is no 8 pin MB power connector? most come with a 4 pin and 8 pin
  9. craig83

    craig83 TS Rookie Topic Starter

    Nope, here's the connectors it's got, I've been told it's not great in another forum

    Cable Connectors:
    20+4pin Power Connector
    4pin ATX12V Connector
    7x 4pin Molex
    2x SATA
    1x 6pin PCI-E
    2x floppy drive
  10. mailpup

    mailpup TS Special Forces Posts: 6,964   +355

    It might be that when you install a graphics card into the second PCI-E slot the first slot downclocks to 8X instead of 16X with a single card. That downclock lowers the electrical demand from the HD 4850 so then it works. So maybe your power supply is having trouble supplying sufficient power to the full system.

    I had trouble locating your motherboard manual so I couldn't verify the 16X to 8X theory but maybe you can check yours.
  11. craig83

    craig83 TS Rookie Topic Starter

    sooo another new PSU might be a good idea then lol? I've been told it's a good idea in another forum anyways because Cit ones have a habit of going very wrong :S guess you really do get what you pay for lol.
  12. klepto12

    klepto12 TechSpot Paladin Posts: 1,115   +9

    i would suggest maybe a 550 watt ocz psu or corsair maybe an antec psu or pc power and cooling there the best imo

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